This makes an awful lot of sense to me. Why would he do this? Because he's been billing himself as a "rags to riches" success story, the kind of fulfillment of the American Dream that's been more fantasy than reality for the past generation. So he has to establish his credentials as a troubled kid from a difficult past who pulled himself up by his bootstraps to become a leader in his industry and should therefore be trusted to make decisions on behalf of an entire nation. If it turns out that he had a not-particularly-troubled childhood then his story lacks credibility.

Of course, if he's not actually running for President but is instead marketing his brand then this sort of "persecution" from the media allows him to play the victim card and increase his stock among the people he hopes will buy his books.