Yes, of course, on a +EV bet, use the Kelly Criterion to size your bet to a percentage of your bankroll.

But it's not that simple. There are humongous unstated assumptions that could determine the result of this particular proposition.

Polymarket rules for this contract say it will resolve based on the overwhelming consensus of major media outlets. What if that doesn't happen?

There's also the issue that statistical models like Nate Silver's function by aggregating polls. This is an unstated assumption that the result will be decided by popular vote.

But there's another scenario where the popular vote is thrown out and the result is determined by giving each state equal weight regardless of population. Maybe the difference in odds between Silver's model and Polymarket is due to the fact that Silver's model doesn't consider this scenario and Polymarket does.

If media outlets don't have overwhelming consensus, then the contract resolves based on who is inaugurated on January 20. What happens if nobody is inaugurated? Or if more than one faction performs the ceremony for more than one candidate?

The rules don't provide for scenarios like these, and it's easy to think of other plausible outcomes that aren't handled.

Maybe the odds really have moved in favor of Trump. Predictit is now 60-44 Trump-Harris. A current Betfair headline is "Trump favourite in all seven swings states for first time".