On many of the blogs I stare at for 15 minutes and claim to read it has been said that D&D has a theme of adventurers who gain wealth and power by plundering the countryside for valuables and danger.
While I will certainly not dispute that this happens in an overwhelming majority of games, and to some extent in my own, I do contest that this style of play is somehow built into the D&D game.
In my experience, the rules for dungeons and dragons are a framework onto which players and DMs can weave their own scenarios. The theme of a game may be the fall of a nation, the danger of ancient knowledge, or anything, really.
One needs only to look at the fabled Appendix N and examine the themes explored in the material from which the game draws.
Will your players become more powerful? Most definitely. Will they gain fabulous wealth? Maybe. Will they seek out adventure? I hope so.
Wealth and power are tertiary, however, to the adventure. The great draw of any RPG is to see what happens next and to decide how your character reacts to it. Everything else is just fluff.