The opportunity to ascend to the third mortal coil is very rare outside the sects and cultivation families. It is not an understatement to say auctions like this are the only ones that loose cultivators will get if they can't afford to buy a slot to harvest in a secret realm.
So most of the people who came are cultivators at the peak of the second mortal coil who are very desperate and anxious. But there are some people at the early stage of the second mortal coil who came for the experience and to try their luck.
There were also people at the third mortal coil who came for the more valuable things being auctioned. After all, the auction isn't only for people at the second mortal coil.
Most importantly, the auction is also used as a gathering and exchange opportunity for cultivators. People could exchange what they have for what they didn't have. So many people attend these kinds of auctions.
