Then hold our governments responsible. I don’t know why anyone would expect a private citizen, regardless of whether or not he happens to have more than $1 billion, to help with environmental catastrophes. In fact I’d expect them to help the least out of anyone, since they have the resources to simply escape if they face danger or scarcity.
There's no realistic escaping planet Earth. Indeed this is a reason so many wealthy people become philanthropists. When someone truly has enough wealth to be free of any monetary anxiety, their concerns tend towards survival/preservation. Both of self and sometimes of humanity. It's ultinately self serving, in that they recognize that humanity's problems can negatively impact their own situations. Broad economic, societal, and environmental failures are probably the biggest risks to their powerful positions. And some do indeed look to ways to escape planet Earth.
I'm not saying that governments don't need to act, just pointing out that the motivations of the wealthy may not be what you expect.
I have a theory that the highest priority most people with wealth (very reasonably) have is "never be financially insecure again" (propagated to their descendants), and that the more wealth somebody has beyond "sustain a comfortable lifestyle indefinitely off of dividends", the more of their money and mindspace they invest into protecting themselves against the long tail of circumstances that could affect that. Applied on a broad scale, with different value systems and mindsets, this explains both preppers ("Society might collapse, so I should do everything I can to ensure that my needs are met in that circumstance" with a little bit of "here's hoping it happens so I have an excuse to shoot someone" mixed in) and philanthropists ("Society might collapse, or even just fall apart to an extent that degrades my control over the means of production, so I should do as much as possible to keep that from happening").
At the extreme of wealth, an appropriately diversified portfolio takes both options into account. If you have $1 Billion and think there's a .1% chance that society will collapse soon and make your money worthless, you're perfectly justified in spending up to $1million to protect against that contingency.
With today's rampant lobbying and propaganda driven news, that's a bit of a moot point. When critical questions are asked of those in power, they're dismissed as asking nasty questions and saying it's fake news. The propaganda is also created to keep citizens fighting against themselves rather than those in power. It's a losing position from a citizens point of view. Either the politicians have to willfully change things themselves, or you need to play the waiting game until the country deteriorates enough until it sparks revolts like in Belarus.
