There is a risk that Coinbase could theoretically empty your cryptocurrency wallet since they control your account’s private keys. However, since Coinbase is a regulated broker, this is unlikely. Both FinCEN and FCA are well-regarded regulatory bodies who serve as watchdogs for THE companies licensed by them. Additionally, your US fiat currency is protected by the FDIC for up to $250,000. (Your cryptocurrency isn’t protected by FDIC.)