Why so many headphones for sale with less than 10 hours of listening time?

Why do all phono cartridges for sale have 100 hours of use?

In my case I read about headphones and heard raves from some people, so I thought I would try them out. Bought a nice pair and a headphone amp to run them. After listening for a while, and trying some very expensive headphones, I decided that I like listening to my speakers much more than any headphone I have heard. I would use them if I had to, but other than that I would pass.

First, I would be highly skeptical of any number of hour claims. Frankly, take them with a grain of salt. Next, there are quite a few headphones that initially sound impressive but with headphones, much more so than most other gear, listening fatigue sets in fast. For instance, those crystal highs turn out to be a nasty rising high end that makes the cans unlistenable over the long run. And that impressive bass, drones and drones. I also think that few people have adequate amplification for their headphones which quickly leads to disappointment. Finally, I would guess that many people buy headphones on line, based on reviews, and without any audition. By the time the return period is over, the honeymoon is also over. 

I could easily avoid this topic but I do have a comment. If someone wants to purchase any piece of high-end audio equipment (at full price), then sell it after only 10 hours use, I'm happy to buy it from them at 50% (or less) of their original purchase price. That's the basis of this website. People are impulsive, and (sorry for the cliche) their loss is my gain. No one forces them to do it. Speaking of headphones, I purchased a pair of Stax 009's on this site for about half of retail. They were practically new and came with the wooden box, extension cord and cover. No complaints here! 

Personally, it gives me no pleasure of taking advantage of imbeciles, either impulsive or not. Those people need help not being ripped off.