Quote from Jaetch
I'm about 1,000 hours on my wizard, and a combined 300 or so hours on the other classes.
I've found two Mempos and two Witching Hours. One Ice Climbers, one Zunimassa's Marrow, one Inna's Vast Expanse, one Tal Rasha's Allegiance.
I've never, ever found a Zunimassa's Pox, Ouroboros, Immortal King's Irons.
People buy in bulk. Constantly. At one point I bought a couple dozen Echoing Furies and Lacuni Prowlers. I spent several hundred millions worth of gold, but I profited about 200-300M after selling off the well-rolled ones. I could have re-invested the gold and repeated the same thing over and over.
There are players who do this on a full-time basis, just like there are players who camp the AH and RMAH day in and day out, or those who camp d2jsp and trade forums for good deals.
Oftentimes, when you buy unID in bulk, you can get a discount. Sometimes, those who get discounts via buying bulk will resell individual unIDs for market value. This is much like real life auctions that feature "bulk lots." Tons of potential profits can be made by reselling individual items within a lot and there are many people in real life who have side jobs dedicated specifically to buying item lots.
Then you probably have owners of bots pumping out their unID loot over and over. They all come from somewhere, but by no means will the average player accumulate 60 Manticores in their playtime. You buy them, hoard them, then either resell or gamble on the ID.
^ This is what's happening. Bots can reach paragon 100 quite easily, that's why gold price has dropped a lot. And also that's why there are so many unids being sold in pages like D2JSP.
Most people just buy in bulks and they get a discount, then they sell it to make profit.