When it comes to stable coins, just remember what happened to UST back when Terra Luna has been attacked causing the project to be destroyed in just a matter of days. Just remember what happened to USDC days ago when it de-pegged from 1$ to as low as $0.87. We've also seen DAI got de-pegged as well. I guess this is enough proof to say that stable coins aren't really pegged to a dollar.

I don't know why investors are preferring holding stable coins than cash. Maybe the potential interest that they can get while holding it in some wallets or exchanges is the reason of it, but overall, I don't think that's a good thing to do.

I can't imagine our world without any cash. Yes digital cash is becoming more popular already and the number of people using it exploded especially during the pandemic where there is a time where establishments aren't accepting physical cash because it might be a potential carrier, but overall, cash is still needed, and it isn't trash at all.