What's interesting about your question is both the variety of answers, but equally how many of them are unimplementable. Probably the easiest to grasp, and (in

What's interesting about your question is both the variety of answers, but equally how many of them are unimplementable. Probably the easiest to grasp, and (in theory) the easiest yo do is "give it away". But even this is much harder to do, and more complicated than it seems. For example injecting substantial cash into a local economy leads to inflated prices. For example revitalized neighborhoods (gentrification) leads to higher housing prices, driving out the local population. Aid to Africa has shown that in many cases the aid was harmful - inhibiting the growth of local food production etc. If you choose to make say a thousand billionaires, then expect a billion applications. Good luck deciding. Even building infrastructure (like say solar farms or nuclear plants) would greatly impact other players in that space. And ending up with all that energy production in one set of hands would be dangerous. Spending money well is really really hard. Much, much harder than we imagined. Expect every grifter, scammer, organised crime etc to gravitate to your orbit. Filtering value from scam becomes hard. Bill Gates is working on eradicating some diseases via vaccines, which is both clearly achievable, and really difficult (because some areas are hard to work in.) So, it's an interesting question. But equally interesting is that no simple answer is really useful.