Perhaps power itself is his endgame. Like Putin who he envies. Everything Trump does is to maintain and grow his power. This video was enlightening on the subject: https://youtu.be/1iZcXn8uDis

Orwell is quoted in the comments and is prophetical:

Power is not a means; it is an end. One does not establish a dictatorship in order to safeguard a revolution; one makes the revolution in order to establish the dictatorship. The object of persecution is persecution. The object of torture is torture. The object of power is power.

George Orwell, 1984