Isn't there also an effect like the second billion dollar being easier to get than the first? I mean all your points are good but the fact that the system allows you to leverage your wealth to increase it is probably the most important factor to get to $250B.
Right, and the risk aspect is only a second order effect. The main effect applies even when you restrict yourself to low-risk investments: it's simply that the more you have, the more you can invest so the more you make on average. But yeah, higher risk tolerance means you can also aim for higher returns.
Absolutely, the more money you have the more risk you can take. That's fractions-of-a-martingale level money so you can probably chalk up a win before you lose it all. Musk uses the same playbook. Losing is for small fry.
Proverb from my granny to contemplate: the devil always craps on the larger heap.