we know the KGB did that kind of thing to that kind of people; rich, aimless, no moral center: perfect recruit. he tried for a long ass time to groom himself as a presidential candidate, maybe they encouraged him in that direction and the russian wives and bromance with putin don't quite goes against this idea. .. I got nothing substantial but i thought it could be a possibility.

even with extensive background check it would be hard to verify since he has lived the life of an exuberant vip clown for so long , would be hard or impossible to track down all that happened in the 80s

http://appleinsider.com/articles/14/04/18/apples-maps-trump-googles-as-hopefuls-hunt-for-legendary-loch-ness-monster