Consider: A 1st level merc makes 300gp/month (1^2*10 per day, average 30 day month). A 1st level Professional or Crafts-person makes about 28gp a month (average die roll of 10, beginning bonus of +4, divided by 2, per week, calculating at 4 weeks per month). A top of the line 1st level craftsman (+5 stat bonus, +4 from skills, +5 from skill focus and another skill-booster feat, and +2 from masterwork tools) is making 60gp a month.
When the merc become 2nd level, he gets to 400gp a month. The craftsman gets to... 30gp.
No wonder everyone runs off to be adventurers. At 2nd level, a month's salary for a merc is a craftsman's salary for a year. If you survive an entire year of mercenary work, you're looking at 4800gp.