Would there be enough money in the exchanges? Would bitcoin fail?
if everyone withdraws all of their owned assets from the online wallet that it owns may make a slight drop in price but surely it will be for a while because so many want to buy your bitcoin & Fiat.
In reality, this will never ever going to happen as the market is full of investors who are investing their money into this and there is hardly any chance that all of them will withdraw their coins. However, in case this thing ever happens, then this will have adverse effects on the crypto market as the market value of all the crypto coins will start decreasing very much significantly and result in huge loss.