The problem with Trump is the office to which he aspires. He's not qualified for it. If he were running for U.S. Senate on the GOP line, I'd have opposed him in the primary but be willing to vote for him in the general election out of party solidarity.
I take party solidarity seriously. Those who've known me through the years on the internet know how I excoriated those who stayed home rather than vote for McCain or Romney because their conservatism wasn't pure enough. I've stated flatly that such folks were responsible for the misery of the last eight years. So my NeverTrump stance is ripe for criticism as hypocritical. Why won't I support the nominee this time around?
It's because Trump's conservatism, or lack thereof, isn't the issue for me. It's his temperament and hair-trigger temper, his vindictiveness and megalomania. He's too dangerous to sit in the Oval Office and to be trusted with the decisions a President has to make. As a Senator, he can rant and rave to his heart's content but he can't do any concrete harm. As a governor, he can mess up a state's economy and do a fair share of damage, but he won't command a military, practice statecraft or have custody of the nuke codes.
As President, the damage this intemperate, unstable man can do is incalculable. Put simply, when faced by the horrible of choice of Trump vs. Clinton, I am forced to conclude the crucial difference between them isn't ideological, it is simply this: the menace posed by Trump is existential, the menace posed by Clinton isn't. We can survive four years of Clinton. I'm not so sure about Trump. He will rip the fabric of this nation to shreds, pit citizen against citizen, endanger our soldiers, go to war with other nations over trade or some imagined slight.
It is my duty as a patriot and a citizen to do everything in my capacity to ensure Trump never occupies the White House. I won't stay home, I won't spit the bit. I will vote to defeat him. I will try to persuade all who will listen to do so as well. I realize the cost. It is terrible. But there is no choice at this point but to accept and endure it.