There's a word or phrase to describe this idea, but essentially - I play D&D because everyone else plays D&D. I also really enjoy it. It's true of social phenomenon. Everyone is on Facebook is a reason to use Facebook. Everyone is on Twitter is why people use Twitter. If I were to use a dating app, Tinder is the most popular, so it seems like the logical choice.
Having said that, I wouldn't be interested in playing any edition other than 5th, though I could probably play 3.5 happily (or Pathfinder, even though I own none of those books).
And generally, also, I'm a big fan of the fantasy genre. I've played Star Wars, Cyberpunk/Shadowrun, and other games over the years, but I don't enjoy them quite as much as D&D. I don't really know why.