I think it's worth drilling in on this, because I think it's generally too reductive to cut the player motivation down to just "get better stuff." Stuff, progression, all that is nearly always in service to other goals. Personal power is directly correlated with agency; better stuff is very rarely the end goal of what a player wants, it's a sub goal that makes them better able to consistently get whatever it is they do want, and it's universally pursuable, even if other goals aren't currently clear. Our Han may not know yet that he wants to join the rebellion, but if he was independently wealthy it would be much easier to do so, once he's decided to become a revolutionary.
If there's any progression in a system at all, and the player wants to orient themselves to align with the character's desires, then there's always a mechanical incentive to try and get better.