I was talking to a chap about the same thing last week, and my opinion is that the majority of instructors directly employed by a company is very few indeed, maybe possibly at most 3. The rest will be contractors / free lancers, self employed. The question which I was asked was " when do you know you can give up your job, and fly full time ".
The answer as camp freddie pointed out is that many of these guys still hold onto there jobs to maintain a stable income for house and family. My answer is that you know when you can transition over is when you can no longer turn up for work at your normal job, yet be prepared for a pay cut.
some guys can transition after a year, some 3 years , others never because they have a wealthy partner and just play at it.
The trouble is know flying school will particularly tell you the truth about the work they are doing, the guys who are fully employed will get the majority of the work and the freelance guy will pick up the crumbs, until one day they offer you an employed position because another person is leaving.
At this time most employed single engine robbie instructors will be getting paid about 3000 pounds before tax a month, and these people are few and far between. The rest self employed lot will probably do the above for 4 months of the year and gradually slow down to 1000 pounds before tax in the bad months of winter.
lifestyle change not a money maker.
fluffy