From what little I see on the news the damaged substation is a medium outdoor distribution voltage switchyard. It may have a 133 kilovolt(KV) feed with possibly some intermediate voltage circuits (64 or 28 KV) and then local distribution (13.8KV). For a comparison, the voltage in the power lines in a typical street are 13.8KV. High voltage needs lots of clearance space around conductors as it really would prefer jumping to ground than staying cooped up in a cable. That is why switchyards take up a lot of space. There is also the potential for a lot of current going through cables and that creates heat that needs to be gotten rid of. Its also easier to maintain clearances to live equipment (If needed) outdoors. The gear could be indoors and is in some rare circumstances, but the cost is orders of magnitude higher than outdoor gear and the rate payers pay for it.
Most utilities are regulated utilities, that have to answer to state regulatory bodies to justify their transmission costs. They get a guaranteed profit on every dime they spend, so their investors may be all in spending billions but the ratepayers who have to fund it may not like or be able to pay substantially higher electric bills every month of the year every year for what is a very rare occurrence. Far better to manage that risk and keep the rates low. Sure, someone could be at each substation 24/7 bored out of their skull, but that would not stop "bubba" from doing target practice from several hundred feet off. Even if the guard sees it happening is he/she going to be equipped with armor and weapons to deal with "bubba"? Odds are they will not, so all the guard is going to do is maybe collect evidence, but the utility will know in milliseconds that the plant is tripped, long before the guard wakes up.
There definitely will be an investigation of how the utility responded to this deliberate act of sabotage and my guess is at least part of it will go back to supply chain. Up until Covid the way to drive costs of any system was to go"just in time". Why keep a warehouse full of spares locally which costs money when they can be bought from a big central warehouse that is serving multiple utilities?. So the utility pares back on local spares. What has happened since Covid (and even before) is the number of firms actually making specialized switchgear is shrinking and a lot of it is offshore as labor and materials is cheaper. These offshore firms are also dependent on their suppliers and Covid is not necessarily over in those countries so the entire chain is stretch thin. Now add in various large hurricanes in the US like Ian, In many cases the utilities are having to start from close to scratch rebuilding hundreds of switchyards like the one in NC. Throw in Puerto Rico (a US territory) losing its grid almost yearly of late. There really is not enough supply chain worldwide to support these disasters, so it comes down to whomever yells loudest with enough political power gets the gear. What normally happens is the utility has some gear locked away for critical spares but only for routine occurrences and they try to "borrow" gear from other utilities but with what is going on with the weather utilities are far more reluctant to lend gear as if they get caught with their pants down after lending gear out that is needed locally, someone gets fired (or retired if they are high enough in management.
I have experienced supply chain issues on a recent small, combined heat power project, things that we used to be able to get off the shelf or in weeks are now booked out in months or years. We needed a small station transformer much smaller than what was at that substation to supply 460 volt power to the equipment in the station needed to run the turbine and associated equipment, This was a nothing special transformer used all over the place to supply large businesses and institutions. The contractor had estimated pre covid a new one with a 3 month delivery. The project was delayed and by the time they ordered it, the delivery was 18 months. We needed one quicker, so we ended up buying a used transformer that was "rebuilt". Typically, with a small transformer like this, a rebuild is test a used transformer to see if its good or not, drain the oil, replace a few seals, fill it up with oil and give it a paint job. At best the guarantee is 60 days and the cost was 20% higher than new. They probably bought it from a scrapper for scrap value but they could get it to us quicker. We also had issues getting some switchgear and had to rent some to get the plant running until the intended equipment showed up 6 months late.
It doesn't take a lot of schooling or training to knock out a power substation. Somewhat like breaking and egg, the breaking is the easy part, the tough part is putting it back together. Someone could and probably has written a basic set of instructions on how to do so and its probably out on the web. I used "bubba" earlier, that has a southern connotation, but we got "bubbas" up north. A couple of bubbas one day were out hunting and didnt get their deer so they decided to do some target practice at these big insulators on a power line up in the woods along the NH VT border. They hit one and took out a 1000 MW DC line from Canada to the US. It took 3 days to fix it and the economic cost was in excess of 50 million. The authorities did eventually arrest them but beyond a short stay in jail and some public defenders time, they couldnt get money out of turnip so the ratepayers pay higher bills.
On the other hand, us "resilient" folks out in the sticks drag out the generator they bought for $500 after Y2K (1/1/2000) and use it run the house while we sit in front of the woodstove/wood boiler/pellet stove. Or in the case of someone with solar panels and newer technology that accepts a home battery, they barely see a flicker. In my case, I need to flip a couple of switches and run off my solar trailer which is backed up by a diesel and will form a microgrid with my other grid tied solar arrays. I produce surplus power most of the year so I would charge my hybrid off the system when the sun was generating more than I was using. If I wanted to automate it, I could so I would not need to flip those switches. There was the town in Florida that was directly in the path of Ian that barely saw a blip in their power systems because they built a city wide solar microgrid with battery storage similar to my house system on much larger scale, it can be done as long as someone is willing to pay extra compared to regular power service. Bubba in the trailer park will probably chose far lower rates and hope the power does not go out and then rely on a tenuous social safety net to keep the alive. Note the substation is now back on line, standard resiliency recomendations is that someone should have a minimum of three days of survival gear ready to go in case of major storm or unexpected disaster so they would have been set. Sure the news likes to hype everything to get eyeballs but people have to figure out that at some point and probably more often these days they may be out on their own.
I have put in six combined heat and power plants in the last 8 years, two for hospitals and four for large industrial plants, they are all microgrids that can run independently from the grid as long as they have fuel. All six of them can flip a switch and run independent of the power grid. Five run on natural gas, the last one on gas, oil or to a limited amount, propane. They could easily add solar arrays and batteries for storage. Five are so called bumpless transfer plants, when the grid goes away the lights do not turn off. On the last one they have to wait five minutes and flip a switch to run off the grid and then shut down for five minutes when they go back on the grid. The hospitals did it for combination of energy savings and resiliency for a long term grid outage, one of the industrial plants could care less about efficiency but needed reliable power in an area with crappy power quality and the other three really just wanted the energy efficiency. We delivered that to all six. At one plant that is fed by a long power line run through the woods, a large piece of equipment shut down one night after a storm, they called in the electrical superintendent as the equipment would not start up. He came in and it took him awhile to figure out that the power line feeding the plant had been taken down by a tree a couple of hours earlier and that were running off grid and no one knew it. The big piece of equipment was wired to turn off in that case as they can run for half day without it and trying to get it to restart would be real hard on the generator. They now have set of lights on the wall of the control room to tell them if the grid drops out (even though its pretty obvious on the control screen).