That's pretty much all it boils down to. Their lives aren't long, so they want to build something that'll last long after they're gone. As like... a legacy.

[He had been a foolish mortal once, he knows. He may not remember it, but he remembers reading of his hopes and dreams for that future. The old Stefan had wanted to heal people, and to make his world a far better place than when he had arrived in it.

As a vampire, he can't physically heal, but he sure could look into other aspects of it.]

It may not be much of an impact, but it's still theirs.