What’s your PC’s profession? I don’t mean what’s his class; I want to know what your PC does for a living. Have you even given any thought to this question before I just brought it up? Probably not. They’re looking to hit it rich by plundering lost dungeon hordes or by slaying monsters and claiming their loot. In short, PCs don’t have real jobs.
Very few classes are in and of themselves professions. I assume you could argue that Clerics and other divine classes generally work for a church, but I don’t think your PC should show up and demand a pay cheque for spreading the good word.
When D&D campaigns begin they usually start after the PCs have chosen to “go adventuring.” But have you ever wondered what all the adventurers did before they threw caution to the wind and sought out this new calling? Has that adventurer always wanted to be an dungeon-delving Sorcerer or an undead-battling Paladin all his life?