The way to make money on the stockmarket is to buy 1000 shares at 15 and wait until they hit 30 before selling them. This isn’t for people short on cash. It takes a lot of money to get a return and you may wait years to get your money back. You have to check your stocks daily, too.
I’ve been on and off Neopets for years. Having a lot of NP makes it easier. When you see something you want you can just get it, play with it for a little and then get back to your life. 
LilMiss has four- two lupes and two glurts. I admit that I play on her account. More than anything I play the games, get the points, then bank them for her to buy stuff with.
My games: MeePit Juicebreak, Cheat, and the tetris like game.
I had built her critters a grand house, but she demolished most of it. The weenie.
I started neopets at just about the very beginning (anyone else remember the Macy Gray and Bruce Forsythe pets??), and have been off and on ever since. It’s suprising how little was actually added to the site in the past year and half since I last played…
I’ve been playing for almost four years. Sometimes I take a hiatus for few months… as others have said, one gets bored throwing omelettes down one’s pets’ gullets, and one doesn’t always have time to play the games.
I also joined in the very beginning, and made up quite a lot of money for myself. I also submitted 35 stories/articles to the Neopian Times before it got a new editor and I just didn’t like it anymore. Eventually I moved onto a new username (muas) and I play off and on. Whenever I get back on I always expect to find it difficult to catch up, but they really haven’t added a lot.
All told I’ve been playing for exactly 5 years.
Oh, and somehow I have five pets–the limit should be 4. The system doesn’t seem to recognize my fifth pet as actually being my pet when I try to do anything with her, but she’s there. shrugs