He wasn’t a contender last time he ran, he did so specifically because Trump needed the extremist “health” conspiracy type people to win his election, and Trump promised rfk an important position if he dropped out and backed trump. It’s a very common move among power and money seekers to run if they think they can gain at least a few percentage points of the electorate. That means they can swing elections either way, especially in today’s environment where most critical elections come down to a few percentage points, and more and more commonly a few votes on the local level.