All of the reasons can be boiled down to these:
1. My candidate is not as bad as the other Republican candidates.
2. My candidate is better than the other Republican candidates.
3. My candidate is a lesser evil than the other Republican candidates.
4. My candidate deviates less from libertarianism than the other Republican candidates.
5. My candidate leans more libertarian than the other Republican candidates.
6. My candidate is more conservative than the other Republican candidates.
7. My candidate has a better chance of beating Hillary than the other Republican candidates.
Not because his candidate is a principled conservative or libertarian. Not because his candidate is great on a particular issue. Not because his candidate is great on most issues. This means that libertarians who vote in their state Republican primaries are no different from the mass of Republicans who hold their nose in every election and vote for what they perceive to be the lesser of two evils. They are not actually voting for anyone, just against everyone else. But since voting for the lesser of many evils is still voting for evil, I have a better idea. Send a message to all of the Republican candidates by not voting for any of them. And you can do this from home with no effort whatsoever.
8:32 am on September 7, 2015
