It’s impossible to earn that much money, but at some point it’s also impossible to hold or spend. Banks can only take so much safely, so it needs to be placed in companies and investments that require some management and all the consequences and responsibility of running those. Spending it is problematic because it will disrupt whatever market it is injected to, potentially harming a lot of people.

The only real solution is to avoid billionaires in the first place by taxing corporations much much harder.