If the base cannot get "their" candidate nominated, then, excuse me, what should the Party do?
If the views of the base are not the views of the majority of primary voters, on what basis does the minority claim that the majority is illegitimate?
You asked: is it "all about retaining power by any means necessary"? No. But it is about retaining (or regaining) power by the legitimate exercise of personal responsibility for the good of the country.
Doesn't someone, some party always retain (or regain) power in an election? Is there something wrong with that?
If one party is even a nanometer better, or potentially better for the country, than the other party, is there something wrong with desiring that that better party retain (or regain) power?
Is there something good or morally superior about losing power within the context of our constitutional political process?
They could try listening to their base.
However, seeing as how they are hell-bent on self-immolation, they don't need to.