Easy. You can insure only insurable interest. Your house can catch fire at some point in the next 20 years, and Dallas can beat Boston the NBA finals. Both outcomes are unknown now, and therefore probabilistic events. If you buy fire insurance on your house you can try to rephrase that you placed a "bet" that your house will catch fire. But it's a stretch. If you bet on Dallas, how do you spin it to say it's insurance? Can you claim that you are a Boston fan and you insure against the emotional hurt if Boston loses?