I really loved playing SWG - not so much for the game, but for the ‘business’ aspects of it. Whilst not as successful as the OP, I made thousands of $US from the game by being part of a oligopoly.

One of the game mechanics was the concept of ‘buffs’ - basically chemical stimulants your character could consume to temporarily boost critical stats which aided in combat. They were an essential item in PvP (player vs player) combat if you wanted to have that edge and so were in high demand. Buffs could only be made by the ‘doctor’ class and only by the top level doctors. Another critical game mechanic was that the quality of the buff affected how much of a boost you could receive to your stats, and the quality of the buffs was affected by the quality of the raw materials you sourced to make the buff (every resource had a variety of stats - this game was a real minmax-ers delight). The highest quality buffs were the only one that people were interested in buying.

Most of the resources required for the buffs were reasonably easy to find - but there was one which was rare - avian meat. The highest quality avian meat, harvested by killing particular birds, only appeared (real-time) once a month for a few days. Without this avian meat, you could not produce the highest quality buffs.

The first time I made buffs - I happened to time it during the HQ (high quality) avian meat period. I spent hours killing the birds to collect meat. I made my buffs, had a shop near Coronet (the main trading city in the game) and sold out within a few days. And I noticed that all the doctors sold out within days too - and that the last few that had some stock could request extortion prices for their stock. That gave me an idea …

The next month when the avian meat spawned, I parked my character in the main spaceport and keyed up a macro (the game had an in-game macro system). All my macro did was cause my character to shout out every minute “Buying avian meat @ Z credits/piece - sell to my vendor at coords X,Y”. I basically bankrupted myself buying up as much avian meat as I could whilst it was available.

I made up a batch of buffs and started selling them - I ran out after 20 days - but I was now substantially more wealthy! I figured - heck I’m on a good thing - let’s do that the next month. Of course, no good thing goes unnoticed …

The next month, there were three other doctors in the spaceport shouting out that they were buying avian meat. Well this simply would not do! So I basically upped the price I was offering to purchase avian meat above theirs - heck - I was flush with funds from last month so I figured I could out buy them. It turns out I was right - I was able to purchase even more avian meat than the last month and I was able to produce enough HQ buffs to just last the month. Then the third month - this is when the market dynamics got interesting …

By now, several people had noticed that avian meat was in hot demand once a month. In the third month, there were several ‘shouters’ when the HQ avian meat started spawning. Like last month, I upped the price I was willing to offer to price them out of the market - a bidding war erupted, but with my bankroll, I could outbid anyone (although I was cringing how fast I was going through my credits). Like any market, with the prices rising so quick, it changed behaviours - suddenly many of the ‘hunters’ in the game were out killing birds to collect meat. I effectively had my own contractor workforce out hunting avian meat!

By the end of the third HQ avian meat season, I had more meat than I ever had before. I realised I almost had complete control of the buff market on my server so I changed my selling tactics. I made my batch of buffs and started selling them, but I jacked the price up (100% increase) - this time I wanted to be able to continuously sell my buffs to last the full month. Other buff sellers kept selling them at the going rate … so I did the rounds of the cities each night and bought up any HQ buffs which were under my price and added them to my stockpile. By the end of the first week, I was bankrupt although I had a huge stockpile of HQ buffs - but most importantly, virtually every buff vendor was empty … except mine. I jacked my price up even further and did a roaring trade.

Over the next few cycles I cemented my reputation as one of the few reliable buff vendors who could consistently offer the highest quality buffs month-round. With the constant trade and monopoly prices, I was able to further entrench my dominant position each month by continuing to out bid any other doctor who tried to purchase avian meat. There were two other doctors on the server who managed to offer buffs for most of the month, and whilst I never talked to them, I noticed that they never went below whatever price I set. Our little oligopoly had a total lock on the buff market - it was a golden age!

When I quit the game a couple of months later, I had millions in credits which I sold for a few thousand $US. SWG let me play out my monopolistic capitalistic fantasies - how I loved that game :D