More effective would probably to buy yourself (or a person that has political potential/influence with the right intentions) into politics like president muskrat, and do well placed populistic propaganda against the actually evil fossil industry. You don't even have to lie, just do some good rethoric speech, ads etc.. We need policies on a larger level, and I think 10B$ should be enough to gain significant political influence for something that the major mass of people is already behind of, just needs a good spark. I think Thunberg has shown that. Not that we shouldn't of course improve public transport in cities. Additionally do (employ) investigative journalism probably in the same process to give all of this a good foundation..

Ya its a decent start. My point here is the scale of what we're facing. Its going to take trillions of dollars, synchronous action taken by many nations simultaneously and a complete restructuring of the current world order. There's always hope but at this point i'm fairly cynical and don't have a lot of faith that the right people are in charge to even start the conversation.