You’re just not thinking like a narcissistic billionaire.
You see, the financial system didn’t make him a billionaire. His innate genius and talent did. All the system has done is prevent him from truly achieving greatness, with its laws and regulations.
But post-apocalypse? All that is swept away. He can be more than a mere billionaire. He can make the world the way it should be, directly, without the slow, imperfect process of buying politicians and funding think tanks.
And, of course, he will be one of the ones to rise to the top. He’s a billionaire. The cream of the crop. He didn’t just luck into his wealth through family or gambling investing. His inherent greatness placed him at the top, and it will obviously do it again when society collapses.