Thomas Shey
Legend
That assumption is unproven, and at the least, unwise.
To be really blunt: and? Its not like that isn't true of a lot of habits cultures develop.
To be blunt back, if a string of rolls creates a circumstance where an entire group, who has access to incredible feats, powers, and an abundance of game mechanics that prevent them from dying are killed off, you didn't do your work as a DM. (You as in a DM, not you personally.) Could one PC die. Sure. If that is unpalatable, then once again, you didn't discuss it during session zero like you were supposed to as a DM. So as DM, you didn't do your work you were supposed to.
I think you're underestimating the degree to which people don't plan for low-frequency events, but still don't like them.