I say, no fun, no way, no matter what it pays. ... Been there and the damage it does can last forever. ... I know cats who did big bands for big dough and when it was over they hung it up. ... I'd say, "say goodbye" to this guy, before, his 'view of music' rubs off on you.
It depends on whether you're doing it for your friend or doing it for the music. Sometimes you do things for the thing and sometimes for the companionship and sometimes to do someone a favour. If it's the first one then only do it occasionally or stop. If it's the second or the third one and then... you know what to do.