THAT is indeed a REALITY.
Even more real is that MANY TT coaches cannot just coach and afford a car and an apartment by themself. Many have another job and/or live with one or more people in the same place to reduce housing costs. Some do not even have a car. Living in USA in an urban area is expensive. Nearly every city besides NYC and Boston does not have a public transportation system worth a spit and you could argue that NYC and Boston subway/bus systems are garbage. Anyone who has lived in a country and city with a good subway system, like say Seoul would concur. They throw RIOTS over there if they have to wait more than 5 minutes for a train.
Even if you hire on with a big club that houses you (like say the new HUGE 888 club by SFO) and pays you OK (lowest coach you have to pay 100 an hour, they gotta get a goodly chunk of that), even if you can get ahead some financially, when all you do is coach 1500-2500 kids hours on end each day, your reactions and instincts are not that of a 2700-2800 level player.
You simply drop a few levels when you coach full time.
lightspin also makes a great point that MANY will not realize that even if a player had access to pro players for practice partners, even a few hrs a few times a week is only enough training maintenance to get you in trouble vs a pro in competition.