Its only natural that a game as old as UO, with the age of the average player being higher than in most other online game, substantial amounts of virtual wealth will change hands. These arent kids getting allowances, most are adults with good paying jobs. why not spend part of what you work for fun? almost 2 decades of building up items / gold / characters / etc also naturally creates a scenario for very large amounts of what has been building up for years to change hands.
That being said, Gold is also extremely easy come by in game. Much easier than it was even 5 years ago. Even a new character can make hundreds of millions just by playing the game in a couple weeks to a few months.
Ive never bought gold, dont script, dont cheat, dont treat UO as a job, dont even farm or do peerless regularly and still manage to have everything i need and then some. I can say the last 2 years of the game was so much easier for me to make gold than it ever was before. Shame loot was huge. Imbuing had put a glass ceiling on the armor / weapons economy that shame loot opened back up. The market for customized suits is back. EM stuff has gotten bigger and flashier and fetches more gold. Theres so much gold changing hands that even non-collectors like to have some nice things. even more gold changing hands. Then difference between the "haves" and the "have nots" is shrinking, which is a good thing but also drives up prices. More people being able to afford stuff means more demand, which means higher price. Theres also of course less players overall, with the bloat of 20 years and gold and items. a natural cause of inflation.
So yeah stuff costs alot, theres always a few who make a splash with higher than average spending habits, there are still good deals to be had all the time and its easy as hell to make gold to spend on whatever. armor, that one very expensive rare to indulge in, or to "reinvest" in your virtual wealth. Like real life, it can be fun just to see how much you can make from starting out with nothing.
Whats awesome to see, is that theres actually new people interested in both armor and rares. Ive only been seriously in the rares game like 2 years. So im even newer, and know that rares and high end pvp is a hard thing to get into. Its refreshing to see that UO is still fun and interesting enough for new faces to show and get into the heat of it.