Tribute bands can make a very good living......an obvious reason why there are so many. Principles are great and I admire people who only want to play their own original stuff...but at the end of the day professionals play whatever makes them the most money. Show me any job or profession where people are entirely happy with their lot. I cannot think of any.
As with any job we sometimes have to do things that perhaps through choice we dislike or would prefer not to do. It is a small price to pay for getting paid for performing music for a good living....... far better that than minimum wage flipping burgers during the week and playing free or for peanuts at weekends.
My band has two styles....the one we play for punters and earn money from.....and the one we play for our own enjoyment.

I remember hearing about certain famous bands who hated being on the road.... complaining about having to tediously play their own OLD hits over and over again BECAUSE THAT IS WHAT THE PAYING PUBLIC WANTED.
To be a success you have to play what the public want....NOT what we necessarily want.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055