I didn't do anything at that scale, but I did sell a manastone to a guy in Korea for $450

I had ShowEQ up and running on a Linux PC right next to my main PC - a pretty sophisticated packet-sniffer that would decode encrypted network traffic coming into my house - so that I could see all the network traffic that I wasn't supposed to be able to see; stuff like rare spawns, and even things like which mobs might have rare drops on them. I learned a lot about networking trying to hack that game
A couple of years ago I went back and played Project 1999/Everquest Titanium for a bit - soloing with a bard - just to feel the rush. It isn't the same, but I still remember how it felt. Note that Everquest, for all of its success, was never a mass market game. At peak they had about 100,000 active accounts. Still, for the time, it changed the industry. When World of Warcraft released in late 2004 it more or less crushed all online RPG competitors, and was easier and much friendlier. World of Warcraft was pulling down numbers 100x as large as what Everquest ever achieved. I played WoW for quite a while with some of the old Everquest development team members. The fact they haven't developed a WoW II is almost criminal, in my opinion. I've been waiting for one for over a decade