Why they don't charge any fees? I don't use clubhouse (Android) but if I were user I would be happily paying 1-2% fees and would rather prefer seeing service has source of income.
For an early-stage venture-backed startup a small amount of revenue is worse than zero revenue. What the CEO has sold to investors is slices of glorious future potential. But once you have cold, hard cash coming in, suddenly people start evaluating you as a present, actual thing. And in practice, the amount of money coming in from a new, experimental product won't do shit to drop your burn rate. Better to stay in the land of glorious potential until you're sure your revenue graph is going to be the beloved hockey stick.
Because VC. You need growth, at all cost (both monetary and ethical) to get more VC money, and when you’re big enough you exit by selling to a big tech. That’s current Silicon Valley playbook.