...I mean, if you use an online wallet, it way safer that having it stored on a file or paper which can be stolen at any time.
Oh my GOD no. You're completely backwards on this. No no no. Online wallets are all centralized. Just avoid them. Make 100 copies if you're worried about losing a paper wallet but don't store anything you care about on an online wallet. Look up the 1000s of examples. Just Google it.