Don't let the best be the enemy of good. Lets start with the villains we know. I can kill/imprison the rest later.

As a species, we need to find a way to manage power, so that it isn't handed to the greediest, most dishonest, most evil and irresponsible people. If we are to survive as a species, we have to do better. It's not that we're fundamentally incapable of solving the problem. But the people currently in power will fight tooth and nail against any attempt to find or implement such a solution, since that will mean the loss of the power and privilege that they value above all else. The point of the fantasy scenario described is that without the ultra rich running interference, we'd have a better chance to improve the world. It's still a tough problem and requires large scale societal change such that business as usual doesn't continue as you described. Better education to make the public more aware, coupled with a few key changes to how governments work could give us a fighting chance though.

Sounds like step one in a long process