Most of the world’s major problems literally cannot be solved by an injection of funds alone.
It’s about what that amount of money would go towards: education, healthcare, housing, food security, environmental protection, wildlife preservation, social programs, etc.
… how it would now help, but not solve.
We can solve these problems with targeted funding that gets to the root of the problem. For example, rather than simply distributing food, you educate and equip communities with the ability to grow their own. Even low-cost water purification in some parts of the world can make a massive difference to literally millions of people.
Lifting people out of poverty, even by having a universal basic income, would solve a ton of issues facing those populations: low education, poor health, food security, programs for kids/teens, more equitable transportation, etc.
We’re not talking about sending off grands for a few thousand dollars or even several million. We would have TRILLIONS to use towards implementing solutions. And that money would continue to come, because these rich assholes collect and hoard money faster than anyone can spend it.