overgeeked
Open-World Sandbox
I think that's a key part of this that gets constantly overlooked or lost in the shuffle. If your joy comes from simply collecting, sure. If your joy comes from simply reading, sure. If your joy comes from solo play, sure. But if your joy comes from actually playing with other people, not so much. The canard that you can buy an RPG and play it forever is so ridiculously false it smacks of white-room theorycrafting.In terms of received value for money, sadly it doesn't look good. The core rulebooks of almost all the systems I own have been absurdly good value. But almost nothing else has been - most of it never saw use at the table, and most of what did see use was only a few pages out of a big book in a handful of sessions.
While it's true that a certain few core books are absurdly good value if and only if they're attached to incredibly popular games, it's absolutely not true that all RPG books are absurdly good value. There's a massive disparity between D&D, D&D-likes, licensed games of incredibly popular IP, then a massive drop off from there. As you say, most of it never sees use at the table.
You can fairly easily find a game of just about any edition of D&D, with a few notable exceptions. So the core books are incredibly good value, player-facing supplements slightly less so, DM-facing supplements slightly less so, etc.
Niche games or less popular genres? Forget it. You better love staring lovingly at a shelf full of dusty books because you're never going to get to play most of them.