I think he completely misunderstood 15 minute cities as a concept.
15 min cities mean cities that are mixed use enough that you can get all your needs within 15 mins without a car. Cities like this can be large and typically are extremely well connected, not isolated into enclaves like this person suggests.
In sports betting you are betting against the house. If the sportsbook sets a bad line, you can lock it in and make money off of it.
Horse racing is what you describe, parimutuel, where the house just takes a commission. But the odds shift even after you place your bet. Very different for traditional sports betting.
15 min cities mean cities that are mixed use enough that you can get all your needs within 15 mins without a car. Cities like this can be large and typically are extremely well connected, not isolated into enclaves like this person suggests.