“Years of not paying lawyers”
That’s the only reason I can imagine for a lawyer not wanting to work for Trump.
If someone can give other reasons I’d appreciate it.
He's also known to try to bargain down his bills from contractors, including lawyers, because he thinks that's just how it should be done. Most lawyers don't mind negotiating on bills if they think a charge is excessive, because they like to keep the client happy. But if they feel that the work billed was fair, and the client still wants to try to push for a bargain, they're not going to want to deal with that.
The other thing to go along with billing is that Trump's very nature is going to generate a lot of legal work because he is somewhat...impulsive. Just in casual conversations with other conservative lawyers, we've kind of all laughed at the prospect of how horrible a client he would be.