It's not that it's impossible to for online wallets to be secure, it's that most of the people implementing them are amateurs when it comes to security.
The Bitcoin industry needs bank level security. They're doing some things right (most exchanges offer 2FA), but they've got a long ways to go.
The Bitcoin industry needs bank level security. They're doing some things right (most exchanges offer 2FA), but they've got a long ways to go.