The juiciest alphas I've ever traded were sports betting. Some of them still exist, but it quickly becomes an infrastructure problem (ie. how to bet with size > $10 and not get limited/banned) rather than a modeling problem. And don't forget to include taxes in your EV 🙃
betting sports is just like trading. you gotta buy too cheap and sell too rich.
if you manage to do that consistently and not bet too big, you will make money over the long run.