You'll die faster dropped into boiling water than watching over hours as bears eat your guts and then wander off once their sated.

I assure you, getting eaten alive is far worse than boiling to death.

Venturing into the wild without good weapon is not a smartest thing to do. The problem I'd that weapons that can quickly and effortlessly kill the bear are often unavailable to general public.

...ordinary medium-to-large caliber hunting rifles are unavailable to the general public?

Depends on the country, territory, season.