Then you can get rich by betting against it, so most people seem to disagree with you. And in a democracy most people decide who the next leader will be.
betting markets aren't "most people"
Why would you assume that the parent (1) has a gambling addiction, (2) has enough side money they can lock into a far-away bet and (3) wants to place a bet that will more than probably never pay anyway because it won't be insured nor escrowed by a trusted third party?
Buying or selling stocks of companies owned by MAGA henchmen is probably much safer.
If I interpret the odds correctly the site is saying Newsom has 22% chance and Vance has 20% chance. These odds seem rather low.