At higher level, skills come faster than you can sell. But I am not sure there is a massive drop off in markups, I still sell chips regularly.
Skills do matter though. Sure anyone can run around with high DPS, but without skills, MA wins over time.
Once you get skills, you can start to win.
I do think that maybe PM token winners should be forced move on to the next cat, or be prevented from winning pm tokens for the next season or something. So at least others within their cat have a chance at PM tokens (before prof/hps kick them out), and the same players using borrowed gear cant keep winning the same cats over and over, by staying in the same cat perpetually with a few chips...thus the overflow of skills for sale.