I read a book by a journeyman NBA player a few years back, and playing ball overseas isn't what most people think it is. Unless you're going over there as an established superstar like a Marbury or Amar'e Stoudemire it's a rough life by pro athlete standards. The little things like taking road trips in cramped buses with no A/C or heat, flying in coach on commercial airlines, teams trying to take advantage of you monetarily, extreme fan harassment, etc. make picking the NBA an easy decision.
If I remember correctly, the guy that wrote the book left a guaranteed 6 figure contract in order to accept an invitation to the Lakers training camp with no guarantees of anything other than an opportunity to the make the opening day roster. Unless you just really love playing basketball there's no way you're turning down a spot on an NBA roster to play overseas. At the end of the day no other league is going to give a fringe player the type of lifestyle that they would have in the NBA.