A recruitment business can be an extremely profitable one, as with all businesses you need to make sure there is supply and demand. If there is no demand (no clients needing assistance to recruit or willing to pay for recruitment services) or there is no supply (no candidates willing to do the job) then your agency will never take off. However if you get the correct niche your life as a recruiter will be so much easier!
Follow this video to see how easy it is to actually find the best sectors with very little competition.