It’s not that they “readily abandon everything they say they believe in and hold dear to”, it’s that they’re making the best of the terrible hand they’re given. Who else to endorse? someone with zero chance of winning? 90% of voters choose by party line, not who’s running ... so those 1% of voters who would rather “vote our conscience” will have no effect beyond bettering the odds of the one viable candidate we dislike more.
Your viable choice is Mitt or Barack. If you opt for “neither”, you’re failing to help the one of those two you dislike less. If you hold your nose and vote the one you dislike less, you’re not “abandoning everything you say you believe and hold dear” because you’re doing what you can (however little that may be) to ward off the candidate even more opposed to your principles.
Thank you for a reasoned answer. Have you read the thread? It appears
most don’t agree with your reasoned response.