“So how does he win them this time? Unless you can answer that, voting for Trump would seem to accomplish nothing more than virtue-signaling.”
You choose to ignore the obvious. Trump is creaming DeSantis in the polls. DeSantis will lose, and that’s when you will figure this all out, when your choice loses bigtime.
Trump is beating Desantis at this time in the primary race (polls this far out are notoriously unreliable - otherwise we would have had President Giuliani, President JEB, President Walker, etc.), but Desantis has a much greater opportunity to win over the Independents, moderate Dems that are tired of Biden and the Never Trumper GOP in the general election. Desantis may lose the primary, but Trump will lose the general, and then we all lose.