Most sports betting markets have a degree of unpredictability, and bookmakers will ban sharps (those falling outside the statistical norm or continually hitting lines just before the market moves).

Betting on a final score in most markets is fine.

When betting gets extremely narrow and specific e.g. "Player X will be subbed on for Player Y" it gets morally dubious.

There is a lot of overlap with insurance markets. The incentives have to be aligned (life insurance) with sensible guard rails against abuse (cooling off periods to be covered for suicide)