I think amongst all the things mentioned, the user makes a huge difference too. Not saying that's your issue at all. I take really good care of my mods, and I have an iPV3 from December 2014 thats kicking. Hell, my MVP 2 still works, and I do use it occasionally. I have a good amount of mods, both mechanical and regulated, too. A good sample size
I don't believe I have ever had a regulated mod die. I have gotten a couple ones which arrived non-functional in one way or another, and needed to be sent back and swapped. Thats only 2, and they were replaced since they arrived broken. That's the closest I've had to a regulated mod failing.
I have had an unregulated series box go on me. The switch had a failure inside of it, causing it to arc and weld itself in, thus auto firing. I ripped my batteries out immediately, and my mod proceeded to fry the mosfets and stink up my room. That was a hand made U.S.A. box, by a reputable mod maker. I have a replacement and love it. I use that example because it was a hand built nice mod, dual mosfets and very clean work. It went on me at the switch. A .50 cent part almost put me in a bad position. I can't fault the mod, the switch is the same Mitec you see on boxes all the time. Mine just had something internal fail and it shorted. Bad luck for me, I'm glad myself and my property are fine. But expensive and USA made don't equal an inability to fail. Nor does China and budget mean a definite failure.
I think it just has too many variables. Kind of luck of the draw. Some people think you should be able to drop a mod and have it work. I see that as I'm lucky if I do that and it doesn't break. And batteries go, usb ports go... on and on. If you take care of a mod, keep it clean from juice, etc... it should last you. It's the little parts that usually go first, and batteries are finite in their lifecycle, so they go.
I will echo
@f1r3b1rd regarding the Hex Ohm. I have a second hand V2 that's in great shape. Operationally it's flawless. Being a V2 I know it's been around for a while. The 3.0 is really nice too.