In the UK I got quite close to the Theatre World for a while and for Actors in the UK at least the problem seems to be that way more people go into Acting over there than the need for Actors with the result that most earn less than minimum wage in average from Action (which is possible under UK work laws because actors are freelancers and most spend long periods without any income from it between jobs).
Judging by other areas such as Tech Startups and Game Making and from what I know indirectly from the Fashion World, which all seem to be quite exploitative and pay below average for most people working in it, I think all professions that have an image of Glamour (in a broad sense) end up with most of people working there making comparativelly peanuts even if there are a handful of superstars and high level managerial types making tons of money.
Also, by the way, Architects make good money. Graphics Designers, on the other hand, not so much.