It always depends how much money you got in the wallet. People in the crypto space go super paranoid, 2-of-3 signing schemes with top-notch security, hardware legers, metal-plated keys that are burried in the woods etc, and in the end they hold less than 1000$ in the wallet... All safety measures should be chosen relative to the amount you are actually securing.

Even iPhone apps:

https://www.reddit.com/r/Bitcoin/comments/1x46gnh/a_fake_cry...

Not sure if your comment invalidates the context: your iPhone app (or hardware or iOS, etc) could have a bug that was not discovered yet. It's all about attack vectors, and opponent motivation and resources.