The reason this regulation exists is because enough people doing it is systemic risk.
You losing all your money impacts you. You and millions of other people losing all their money at the same time impacts society; they can't pay bills to their creditors, then those creditors can't pay, and soon enough we're talking bank runs and financial collapse.
You losing all your money impacts you. You and millions of other people losing all their money at the same time impacts society; they can't pay bills to their creditors, then those creditors can't pay, and soon enough we're talking bank runs and financial collapse.