I think the problem is more then just one thing, like not everyone buys domains to be a reseller. Most resellers see all domains as worthless, unless the have rank, traffic, and searches. Or they are already built into money makers, and most anything other then .coms ant worth it.
Others buy domains to build them into sites, and yet others that buy them to sell to end users. In that the value is not as high as the best domains, but people would buy them to use them, and they can make money off them that way.
And many people buy them for a mix of all these reason, another thing is good money domains are not easy to come by anymore. All the good ones are taken, and sell at very close to what they are worth. Now most that are dropping, are auction off and heavy bidding for any good ones. Buying at such high prices, is taking a chance so buying cheaper ones, thinking they can sell and make some money.
And if not build them and then sell them, and may be they will hit the jackpot at some point. Many then find it takes time and money, to build them and time to get them sold. Personally it would seem to me, that the money guys are taking a much bigger share these days. The big money guys keep changing the rules, many big name sites have seen big drops in ad money.
They had to make changes, to try and get the income back up. Also the drop auctions, got bigger money guys much more money. And when people find ways to make the money, they are not telling how they are doing it. And the market got many ripe off artist, in it as well so many people very trust.
I'm not saying people don't make money at all, but it become much more work and risk. And full of land mines to get past, if some one took Iamsomuchinlovewithoxoxox.biz and built it. And got it making good money and lots of traffic, with high rank they can also sell it for good money. And some people seeing making $100 x 100, just as good as selling one good .com for the same money.
I go throw drop list for hours at a time, and will agree most all are really junk worthless. And many I get, most people don't see much value unless they are built. And I'm sure it takes time to learn domaining, I'm always learning new stuff all the time. As it's a ever changing market, it hits home when you see some one on this forum. Buy a domain for 10k, and flip it for 125k it's about what you know and risk taking.
10k is not a small investment to most people, bad timing or not getting the right end users seeing it. Could man taking a lose after holding it for while, that happen to many as well already. And the market is getting harder and harder, with more and more people want to make money in it.