Both.
Schools are there to make money. They do it by teaching people to fly, therefore you have to have instructors. If I walked into a bank and offered to work for free and deprive somebody, who had spent upwards of £25K of their own money on their training, a chance to recoup some of their investment, just because I think the job is fun I'm not likely to be popular am I.
The fact that most people need to spend vast quantities of cash to become any sort of pilot be it PPL, Instructor, Airline etc.. shows a great amount of determination and an enormous amount of dedication.(Roy Castle style)
The fact that most instructors will vanish off to the airlines at a moments notice is mainly due to the pay and not the job. There are very few career instructors simply because not many can afford to be. I would have loved to have been able to stay as an instructor for a few years, but I simply couldn't justify it full-time. We make jokes about putting fuel in the car and food in your mouth, but it's not far from the truth during the winter.
I am fortunate enough that now I teach CPL, I/R, IMC etc. and I could make a living out of it if I wished, but the expense occured up to this point means that debts have to be paid.
As a PPL student it is very easy to see the industry in a rosy way. It is all sweetness and light, exciting and new. The reality is that it is an industry like any other. It has good bits and bad. Professional pilots do it for the love of flying, if anyone wants to learn for the glamour
I would gently steer them away. To me it's the best job in the world and the positives far outweigh the negatives, but my friends and family sometimes cannot believe what I (all of us) have to go/gone through to get here.
I hope you don't take this as offensive, but I feel that the thought behind your comments are a bit naive, but as I don't know you personally or your background it is very hard to see where you are coming from.