Same here. Every helmet I've owned were replaced were for:
1. I simply got rid of two of my original helmets after about 5 years that were styrofoam helmets with fabric covers, one a Bell and the other a Performance brand. remember these? They were the first helmets I ever owned (early 90s?) and I had two beause they were cheap and I kept one at my office for rides from there an the other one at home. They were in fine condition,and I believe were adequately protective, but difficult to fit and strap properly.
2. The next one I left outside and the neighbors dog chewed it up. (it was old and ugly so I didn't care)
3. A helmet I bought about 15 years ago, the retention system (plastic parts) broke and couldn't replace them - this was the second time they broke, I was able to replace it the first time. I was also ale to replace the worn padding. Actually I still have this one and have fixed it with strapping tape and keep it as a spare.
4. The new helmet, after just a couple of months, I ran over kit bag with car and broke the helmet that was inside. I replaced it that day with a new one of the same. That was about 10 years ago.

If and when I become convinced that a MIPS helmet is better in a meaningful way, I might get one. Frankly, understanding that helmets are only designed to protect you from a fall on the bike, not a crash from a motor vehicle, I think people put waay to much stock in this stuff. I won't call conspiracy but it's definitely to the financial benefit of bike stores (see the OP) and helmet companies that people think they are not only absolutely essential but need to be replaced for arbitrary reasons. I wear one because it keeps my wife and all the busy bodies in the cycling world happy, it's comfortable, and does provide some protection when I lower the tail gate of my car onto my head after loading up the bike, which is better than none.