Not true.
It would fall apart if every person was Bill Gates.
What productivity? Buffet produces something? He pays less taxes than the average person. You mean life would stop if these people died? World was fine before microsoft/lawyers/buffet/etc. and it would move on just fine without them again.
People just need to defend democracy/capitalism that's all.
No rich people without poor people, no poor people without rich people. That's how it works.