No President has a good second term, so why do you think Trump will?

[eagle7-31]

So, without getting into policy or politics, the reality is that Presidents never have good second terms. There are reasons for this. While in a first term, a President will try to burnish his credibility by appointing Senators and Governors to key posts, in a second term, he's more likely to appoint loyalists who are less likely to say, "I wouldn't do that if I were you." They are more likely to have scandals.

Let's review recent history, shall we?

Obama - Lost the Senate in the midterms. Mired in the IRS fake scandal.
Dubya Bush- Iraq war went south, Katrina, and the economic crash of 2008.
Clinton- Monica Lewinsky
Reagan - Iran Contra, the 1987 Stock market crash
Nixon- Watergate
Johnson - Vietnam, Race Riots, Civil unrest

Obama lost the senate in his first term in 2010. good points on your other examples. but what we are dealing with here is a split term, not consecutive as your examples show. That may be a difference. Time will tell.