Unfortunately, instructor positions are not greatly financially rewarding. This is simply down to the market. Aircraft operating costs have escalated but the market is holding down the price of lessons.
While I think PPL training should be able to provide a living for committed instructors the reality is that it is unlikely to happen short term.
On the other side, most young pilots are NOT interested in committing to long term instructing. This is also a reasonable attitude as most aspire to flying bigger aircraft and develop their career.
Additionally, there is a surplus of qualified instructors so there are several looking for work.
I think in the current market, instruction is almost an extension of the flying training program. For newly qualified Commercial Pilots with Instructor ratings, it is a good way to maintain currency (without paying for your own flying) and gain experience which the airlines tend to see in a positive light. You may not make much money but you will not be paying out either!
It is impossible for ANY instructor to prove they are committed long term to training.
The reality is that those instructors who are committed to doing the instructor job right, both for the student AND the school, always seem to be the ones who progress to the airlines!