If they are unemployed they at least get the extended benefits on that front...and depending on the state those groups can be funded by tax dollars. New York taxes have a dedicated amount set aside for arts and entertainment.
Honestly, most actors, musicians, dancers (even on Broadway) dont make very much. Maybe the top violinist makes a good salary...but the Tuba player is probably making crumbs.
I had an old girlfriend who sang in the Chicago symphony choir. She was 1 of a thousand people selected to be in that role...and she made minimum wage. Being an NFL Cheerleader or Vegas Performer falls into that same category. People do those jobs because of their passion for the craft - not for the money.