An example is that professional photographers don't "baby" their cameras. The corners are dinged, everything is worn, and they pick them up in one hand without putting the strap around their neck to stop it falling. If it's too fragile to use, it's too fragile.
My application of this philosophy is that I don't put a protective case on my iPhone. I typically buy the most expensive model, and I have dropped them, and even scratched the screen.
But here's the thing: the bare phone is beautiful. It has a very well designed glass and metal body. It's shiny. It's elegant. It's as small as it can be made.
If you put a plastic cover on it, the phone gets bigger, heavier, and uglier. You're sacrificing something (usability, comfort, appearance) for the benefit of the device, not for your own benefit.
PS: Everyone I know who has a protective case on their phone has broken the screen at least once. Typically they just get it repaired for ~$100 and then... they still have their unblemished pretty phone again, which they put back inside an ugly case.