Powerbuilds can also earn caps. And lots more than crafters. It will change soon I hope but even if crafting was more profitable, people would just get bored over time with their one crafter. They would just craft, and maybe kill some weak NPCs. But then this moment comes, when you want to exploit more of the game's possibilities. Serious PvP is one of them and you can't do serious PvP with a crafter.