He is the end product of 4 forces over the past generation in the United States
1. Anti-intellectualism - This does not mean he is stupid, it means we have shifted away from putting stock in logic, reason, statistics, studies, etc. in favor of emotion. Trump thrives on how people feel and never concerns himself with getting facts right as long as they fit a world view.
2. Partisan politics - This has always existed, but the past generation saw party divide grow in large part to "safe seats". Suddenly parties were being influenced more by the fringe elements of their part as opposed to being centrist to appeal to moderates. Trump again succeeds in part due to the right wing being emboldened.
3. Anti-establishment - This has two parts, being against party establishment and against establishment structures such as the media. People in general have become disillusioned with their parties, and on the right this mean trump and Cruz have benefited while a Bush or Rubio struggles. It also shows in how Trump ignores media criticism never backing down or apologizing because the media is "the other" or opposition in many of his supporter's eyes.
4. Shifting demographics - The baby boomers dominated policy from the 60s to the 00s. Now we see a new generation with very different views and composition. The country is less white and less christian than it was 50 years ago. This amount of change always has a backlash as people fear the new, different, and unfamiliar. Attacking immigrants and minorities (racial or religious) is nothing new, but it works better among the right during times of change.
In summation, Trump would not have happened in 92, 00 or even 08. He is his party's leader because of the path the US has been on politically for a good 30 or so years. I thought he was a joke at first, but longer he lasts the bigger statement he is making on American culture and the US political scene.
