Wow, I genuinely thought I was in a time machine reading this thread, absolutely nothing has changed in light aviation economics since 1990 which was when I started out on the old self-improver route.
Little regional flying clubs struggling to exist, FI's on less than minimum wage (well, thats an improvement on 1993 when FI's were paying flying clubs for the privilege of teaching), will the punter pay xx£ for lesson etc.!
You certainly can make decent money in GA, a colleague, who is an FO, purposely has a 75% contract so that he can keep his well paid FI work going, but he is doing the creamy work, examining, IR, Aero's etc.. Just the same 30 years ago, there was a small group of guys who had the right qualifications to make a reasonable living. The bottom feeders, like me, doing the 5th session of circuit training or trial lesson of the day, were never going to do anything other than subsist until we moved on to the airlines.
I'm a bit sad about this as I'm coming up to retirement, with thoughts of returning to GA/FI as a hobby (which will do nothing to help the current FI's maintain their pay, but there again the retired BA skippers who used to keep their hand in flying turboprops didn't worry too much that they were preventing me from getting a quicker command). Perhaps I don't need the aggravation and will just pay the man and fly his plane every now and then. That micro light is looking quite attractive!