Arguably you can do both, if you let the community sustain the old thing (like what Carmack did with Quake).
For games like Quake 3 it was quite open before it was old. The game was community mod'able during its prime. You had mods like OSP being "the" mod for competitive game play (1v1 DM, Team DM and CTF). It being fully open sourced later on was icing on the cake.
Wikipedia said it sold 319,970 copies for about $15 million[0]. It was a 1 time purchase game for like $50 at release. It took 1.5 years to make with a team of 9. Not a bad turn out for a single purchase and open game with a self hostable server component. Keep in mind that was 20 years ago when gaming was way less popular.
1. Success is not guaranteed. At all
2. Things enjoyed by the masses don't need additional support to stay alive