Personally, I think it's a mistake to think you can make a fortune writing games with Dark Basic, (and I know that's not what you are suggesting)...
It's nothing to do with Dark Basic either - it's the same for any language unless you have a team of very highly talented programmers, artists, musicians and 3D modellers. And of course a couple of million quid to spare.
The buying public have a very high expectancy for games software these days - they are used to epics.
I'm one of the older members of the DB community (if not the oldest) and I can honestly say that when it comes to games, even when teams have got together and said what they were going to do, I can't remember one team ever completing a project. I'm sure someone will correct me if I'm wrong, but the point is, very few team projects ever get completed either.
If you are on your own and are very patient, you might get something finished. Unfortunately, very few people actually do and my congratulations to those who succeed.
I can't speak for anyone else, but for me DB is a bit of fun - totally hobbyist.
If I want to make money, I write Delphi software. If I want a bit of fun, I write DB software. I give my DB software away and if it helps someone else out, then it's a bonus - though most people don't want it! Lol.
Good luck to you though - whatever you end up attempting!
TDK_Man