Well, we're not going to know with 100% certainty for many years into the future if the climate change proponents are right or wrong. If they are right and we did nothing, then we are likely in some deep trouble.
There is a lot of emotion around this issue, and most people have already made up their minds, so I won't try to change any opinions. But I'll tell you what my opinion is and why I think that way. You can take that for what it is worth.
I think of this issue like a fire insurance policy for my house. I'm sure that I could find some people who will tell me that they don't have fire insurance for their house, and that I don't need it either. Or I could find some "experts" who can tell me that fire insurance for my house doesn't make very good economic sense since the chance of a fire in any given year is so small. I bet if I searched long enough on the web I could find people talking about how fire insurance is just a conspiracy for big insurance companies to profit from us little guys, and maybe even find some white papers or articles asserting this.
And yet, I choose to buy fire insurance for my house. $500 a year for $100,000 of insurance to ensure that if a fire were to occur, I wouldn't be financially ruined and would be able to rebuild my house. Most people have seen enough evidence of house fires and know of someone who had a house fire to know that it can happen and that it is best to prepare for it.
The amounts being discussed to mitigate carbon dioxide buildup in the atmosphere can be thought of as "insurance". Sure, it's a waste of money if the climate change proponents are wrong. But if they are right, the ramifications are pretty unimaginable.