Ether is not stable.

However, almost half of Bitcoins in existence have been stolen by exchanges. Mt Gox alone was almost a billion dollar theft. Granted a lot of funds are lost by screw ups to date I personally know many people who lost their Bitbay from forgetting to backup or losing a backup.

With that said we have video tutorials on best practices. Print keys on paper, use M-Disc and so forth. When in doubt, back up and never leave funds on exchanges. Even Coinbase is known to freeze accounts Chinese exchanges deny withdraws and at any hint of regulations it will happen again.