Many here are suggesting that they do not keep anything on exchanges. I doubt this. They must be having good amount on exchanges. They operate with huge amounts and must be involved in trading crypto also. It will not make much difference to their net worth even if they loose funds on one exchange due to hack. They keep the risk versus reward ratio in mind before taking such decisions. Keeping the money idle in hardware wallets or paper wallets will give them no returns at all.
You forgot if not every people who own Bitcoin will join and post in this forum, there are
48,138,066 funded Bitcoin addresses on October 20, 2023, while there are only
52,001 active users according to BPIPIn my case, I never hold my coins in centralized exchange, it's not worth to risk all of my coins just to earn small amount return e.g. 5% APY. I'm not a trader too because I will need to keep watching the graph and check the price every minute which I'm not used for that.