Did you forget just how easily the oligarchs provided hundreds of millions in funding for the Notre Dame when it caught fire this year? It doesn't deserve that funding, but climate change does. The oligarchs splurge like there is no tomorrow.
Mostly oligarchs invest their money in companies. So, they own shares. They could sell the shares to someone, and then they have money.
So, suppose you had a net worth of $10 billion in shares. You now have the same in liquid wealth.
How do you stop climate change? You seem to think it is easy to do with money, pieces of paper and ones and zeros in a bank account.
What do they buy, off the shelf, that solves the problem, easy as that?
You could perhaps buy rights in an oil field and then refuse to mine it. That would help.
You could fund research into solar cells or invest into the market. Though investing money isn't what makes a venture successful: customers actually have to buy the resulting product.
So how do you use your $10 billion to make people stop buying carbon? You seem to think it would be very, very easy. So tell us what practical step they could take, on their own without popular support. Simply by being an oligarch.
Ten billion isn't that much money compared to the problem, but you can do some smart things with it.
I just wanted to show OP that the scale of the problem isn't something oligarchs can "easily" solve.
And let me assure you they have lobbyists.
Meanwhile, you have $10 billion to spend, once. It isn't an annual flow of money.
More renewable investment is helpful! But I fail to see how oligarchs could solve the problem as simply as you suggest simply by investing in renewables and lobbying.