Trump isn't running as a libertarian or Tea Partier, he's running as a conservative nationalist. The GOP base doesn't want significant cuts in Social Security or Medicare, and most want increases in defense.
This was also true during the Reagan years. Remember how the GOP lost the Senate in 1986? By threatening to reform Social Security.
There are even better political reasons to leave entitlement spending alone for the time being. Hint: look at the age of the GOP base.
I don’t care about libertarian, Tea Partier, conservative nationalist, GOP or even ultimately Trump. I care about America and a rebirth of freedom. That means blowing up the status quo (the opposite from the apparent meaning of “conservative”).
If the end game of this Trump Movement isn’t the 80%+ reduction of the mostly unconstitutional $4 trillion central government, the reinstatement of the Constitution as the Supreme Law of the Land against the feds, and the reinstatement of constitutional state sovereignty, then this Trump Movement will merely be a speed bump on the Road to Ruin.