Almost every problem in the world would be dealt with meaningfully if we outlawed billionaires.
Everytime I look at small problems or big global problems, if you follow the money trail, it all leads to some billionaire who is either working towards increasing their wealth or protecting their wealth from decreasing.
Everything from politics, climate change, workers rights, democratic government, technology, land rights, human rights can all be rendered down to people fighting another group of people who defend the rights of a billionaire to keep their wealth or to expand their control.
If humanity got rid of or outlawed the notion of any one individual owning far too much money than they could ever possibly spend in a lifetime, we could free up so much wealth and energy to do other things like save ourselves from climate change.
I've worked for a few small business tyrants that did horrible things as well. It's more of a system issue. Billionaires do the most damage of any individuals, but I think it would be pretty similar if CEOs made small amounts of money (the corporations themselves often lobby for their interests), or if there were only small businesses (they'd probably just form national organizations to lobby for their shared interests).
I agree with the idea of compensating someone who worked at managing an organization ... it takes work, talent, education and experience to do that and do it successfully.
What I don't believe is in rewarding leaders who led their organization, business or corporation into ruin while punishing those who worked under them.
The current system rewards and encourages bad immoral behaviour and we wonder why the system is bad and immoral.