Why is DarkRP so popular?

I like DarkRP, I've spent a lot of hours playing it though, and now it's kind of boring, I love playing MRP.
At the moment, I'm kind of stuck to DRP as I own a server on the gamemode, it's the most profitable because it has the most users playing, and is the biggest fan played game on GMOD.
However, I wish other game-modes were more popular because I'd never really play DRP that much anymore, despite me enjoying it for years.