I have never used a case, insurance, or screen protector (aside from the one pre-installed on the N10+). I have never broken a phone or ended up with a scratched screen (though I have gotten a few micro-scratches on the rear glass). Sure, I know it'll probably happen eventually. But by then, I will already have saved far more than the cost of a new phone (let alone the cost of a repair) simply by forgoing years of extra expense for protection. So I'll end up spending less money for the same benefits.
But that strategy only works for me because I am able to avoid dropping my phone (on average, I do so less than once a year, despite heavy indoor and outdoor use). If I couldn't manage that degree of safety, I would either put up with the additional cost of protection, or else settle for a less expensive phone.