What happens to money left in an account nobody uses

An account with no activity for a stated period is treated as dormant. Depending on the operator and the jurisdiction, that can mean a monthly administration fee against the balance, a requirement to re-verify before withdrawing, or eventual transfer of the balance to a regulator or the state under unclaimed-property rules.

Dormancy rules exist because an untouched balance is a liability an operator carries indefinitely, and unclaimed-property law is the mechanism by which money that nobody is claiming stops sitting on a private company's books. Neither is designed as a penalty, and both are capable of consuming a small balance entirely.

It does not mean the money is confiscated. Where a balance transfers under unclaimed-property rules it is generally reclaimable from whoever holds it, but doing so is a process against a government office rather than a withdrawal.

The problem arrives next. Small balances get left behind deliberately — the amount feels not worth the withdrawal — and that is exactly the size of balance the fees consume. The decision not to bother is the decision to give it away.

What to do with it. Withdraw the balance and close accounts you have stopped using rather than leaving them open with money in them, and keep the closure confirmation.