I'm also a no case person. I don't remember ever dropping my iPhones. But it is not for everyone. Once a friend took my phone to look at something and he dropped it, shattering the glass. I was more amazed that in its entirety of 3+ years, I never dropped the phone once but it slipped my friend's hand in just that few minutes. :-)
I’ve broken several iPhones including one the same day I got it. The breaks always seemed to happen randomly. Relatively low impact. But once I dropped one, tried to grab it, and ended up flinging it up and across the room where it hit the wall about ten feet up then fell anyway... it was fine. Another time I was hiking and stupidly had my phone out. I fell, landed with the screen side down beneath my hand onto pebbles... not a scratch.
My case on my 6s finally broke a few months ago after 3.5 years of (ab)use. In the whole time I had it, I dropped it maybe 5 times. In the week after the case broke and I took it off, I dropped it hard at least 3 times.
Suffice it to say, I got a replacement case real quick after that.
LOL. He is a really really good friend, a really good person and someone doing a lot to help curb climate change. We were both nervous after YC Interview that day in Mountain View (2018).
He insisted paying for the screen replacement but I didn't let him. I got the battery and screen replaced and my iPhone is on to its 4th year. :-)
