I mean, he is makings ads telling people to not vote for him, and instead to vote for Trump. If you cared enough to vote for him, I would think you would believe what he is telling you there.
Given his overall goal of not letting the Democrats win, this is a reasonable position for him to take. It is also reasonable for his supporters to vote for him, both to show their dissatisfaction with the other choices, but also because it sounds good for a future race if he were able to say e.g. “8% of people voted for me even though I dropped out”.