D&D had its so-called endgame, in which characters become rulers of their own holdings. It's sort of the like the American Dream. Work hard, don't give up, and your perseverance will carry the day. Of course, adventuring is the "hard work" in this paradigm. It can be its own reward, with fabulous wealth being the goal. It can also be much more, if the player decides to leverage all that wealth into a position of power and authority for his character.
Then, there are games like WFRP, which have no endgame. It is certainly not the only RPG out there like this, but since it is the one I'm currently reading, it is the one I'll be referring to. It states implicitly in the rules that characters will not get rich adventuring. In fact, if they live long enough to reach their fourth career or beyond (something akin to making it to 12th level or so in D&D), it is accepted that they will have:
- Run afoul of the law and be considered criminals
- Be scarred and/or missing limbs, organs, or appendages
- Possess more than a couple of mental disorders from run-ins with horrific creatures and brushes with death
- Be mutated to some degree, if they are wizards
- Be hounded by Witch Hunters (in reference to the previous two entries)
The rules make it plain that there is no financial future in adventuring. The creatures of the Old World do not have a "Treasure Type" or "% in Liar". Nor are they pinatas waiting to burst forth with coin at the first solid whack of a sword. There is no promise of land grants upon achieving a certain level of competence, not even for the Noble or Knightly career paths. The only thing the adventuring life offers is an ignominious and painful end.
So, why do it? From the character's point of view, that is. In the case of WFRP, the answer is simple: because no one else will. The characters begin gaming life as everyman-types, and usually find themselves in precarious situations not of their choosing. Yet, they are also in a unique position to do "some good". Once that happens, the "because no one else will" attitude develops. This is rarely acted out at the table, being more taken for granted as the character's rationale.
Of course, WFRP isn't the only game that doesn't have a D&D-like endgame. I find there to be an interesting duality, though. Many games decry D&D's "kill it and take it's shit" foundation. They make it a point to remove that as a motivation, removing treasure types and tables. Many also do not possess the land-grant endgame. Yet, the character creation and development in such games is designed to produce characters who are more than capable of carving their names in history and ruling vast domains. At least WFRP takes the everyman paradigm and really sticks with it, all the way through a character's life, and never flinches from it.
I suppose it comes down to a question of how do you want your glory. In D&D, it is writ in the legends of the world. Your character has the potential to become truly legendary in the great scheme of things and have his name spoken of in awe for a thousand generations. In games like WFRP, it is likely that no one will ever remember your character's name but his companions, and his tales of glory will die with them. But your character, and his companions, will know he fought the good fight and went down swinging. It may not be glorious, but you can bet your ass it's valorous.