Why?

So I just have to ask, why has this movie generated so many direct-to-DVD sequels? While it didn't flop by any means, it wasn't necessarily a success at the box office and I don't think it generated some huge fan following. So what exactly is going on with the sequels? Are they actually profitable? It just seems strange to me that this studio is milking every last cent out of what is clearly a dead horse. Is the whole sequel thing just a money laundering front or something?