The bet is available on PredictIT. The numbers don't always add to $1 (actually $2 on this market because of the independent) because of bid/ask spreads and because PredictIt's fees make it unprofitable to always push the market to this point.
The answer is not bid-ask spreads, as I said in my comment. The answer is probably substantial hidden fees. But your original post quoted 38% ignoring the fees. If you don't know the details of the bets, it's not surprising that you think that they are good opportunities.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.