Eh, not sure I agree with your police work there. The point of inflection is 1992, and since then every successful candidate has been a newcomer or outsider perceived as disruptive
Obama was broadly perceived in the same terms as Trump by the people who have been damaged the most by the consolidation of productivity gains- disruptive to the establishment order. And you can go back further than that.
Think about it this way: these are the presidents elected since WWII:
- sitting president/VP/Senator
- Supreme Allied Commander
- Sitting Senator
- Sitting President/VP/Senate Maj Leader
- Former VP
Vietnam ends
- Outsider Governor
- Radical Governor
- sitting VP CIA Director, VP, congressman, ambassador, son of powerful senator (return to establishment via next man up)
1992
- Southern Governor
- Southern Governor
- First term senator
- Notorious Celebrity
The relevant historical Trend here is that the white working class has been in political and cultural rebellion since the end of Vietnam and starting with Bill Clinton through Obama to Trump you see the recipe being refined to its essentials.