Over the past few years, it's seemed to me that Palin is more concerned with being a celebrity in the limelight than with promoting conservative ideology. She has her reality shows, Trump had his, so they're a good match.
And I'm not saying this because I'm kneejerk anti-Trump, but because I don't really take Sarah Palin very seriously politically. If making a public spectacle of herself and her family is her goal, then it makes sense to latch onto the candidate who is the best self-promoter.
She has her followers to this day and garnered their votes for Trump. Good for him.