When you walk across the street, you're taking a gamble that a large bear isn't going to come out of nowhere and attack you, for the huge prize payout of safely reaching the other side. Therefore, other things like dog walking and long strolls by the beach are also gambling.

If you made this bet, then got cancer, would you say "hooray, I'm rich!"?

The words for this are hedging and speculation vs gambling.

The point goes like this: you and a neighbor start a business. You each make independent choices on health insurance. When he breaks a leg and can’t work for a while, it’s inconvenient but not burdensome for your shared business. But, you chose not to get health insurance. Your melanoma diagnosis looks like $80,000 which you don’t have. Your business partner has a choice: should he liquidate the business, or act in the long term?

If you paid into the insurance pool, then how is the pay out unearned?

Did you choose to get cancer or fake it?