This might be a generational thing, but I don't find my younger players care about getting wealthy. They've grown up with fantasies that have been about heroism and adventure for their own sake. That's the play they want to emulate.This speaks to motivation, of course. If the PCs' motivation is NOT to acquire wealth, what is it? Note -- I asked the player characters' motivation, so "gaining levels" is probably not a good one unless the game is very meta. "Gaining power" in a more general sense is better, as is, "finding magic items!" because they things that exist in the world. But then the question comes to "why?" Why does your character want power or magic items?
If we aren't talking about quests to save the princess/realm/world on a clock, if the players have agency over their characters' actions in the world, then they need good motivations. "Gold" is an easy one that suggests the kind of places D&D excels at presenting, namely Dungeons and Dragons' lairs. "Uncovering ancient knowledge" and "finding my mother's heirloom sword wherever she fell in battle" are good ones too, but "get rich" is a concrete, understandable, powerful motivator.
Obviously, there are games that isn't the case, especially among old farts like me, when GP = XP and that encouraged a very specific sort of play, but telling younger players -- the overwhelming majority of players nowadays -- that they're doing it wrong if they're not playing like I did in 1979 is a self-defeating strategy.
The generational thing could certainly explain the vehemence of the folks insisting that SimCastle is an obvious and necessary component of the game, since once upon a time, what sort of fortress your character made at higher levels and what sort of followers they got was in the PHB in the class description.