Nonfiction is not necessarily true. When I was young, I flipped off a light switch and a loud clap of thunder happened. Well, I stood there flipping the light switch on and off trying to make it happen again. So two observations do not necessarily have anything to do with each other.
When I see that experts do not agree with each other, it frees me up to decide what I think...some expert out there probably believes the same thing.
So if somebody believes that people cause global warming, it doesn't mean they are trying to make a buck off of it. The person may sincerely believe he is right and that, therefore, the right thing to do is combat it, only incidentally making a tidy little profit. Neither view makes him right or wrong as the facts are what they are and we do not always see the correct connections. It is up to us to do what we think is best without delegating our thinking to some expert.