That's a good distinction made upthread -- death isn't necessarily part of what might be challenging or not, or even what makes it challenging. Death might be an outcome, but it's independent of challenge or difficulty). There's plenty of challenge available without death on the table.
Overall, I would say that what most players want is agency. That their choices not only matter, but have a direct, understandable, and strong influence on the outcome. Players and characters can be challenged, and things might be very difficult, but if it doesn't feel like your actions have much of an impact on whether the character succeeds or fails, then many will tap out to find and play a game (whether RPG or otherwise) that offers it. (And if they're not interested in agency, then a slot machine may be much more lucrative.

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Players who are reluctant for challenges or harsh penalties for failure might have concerns for the amount of agency, perhaps brought on by previous experience. Or they might just not understand this particular's campaign style or tone. I've found that a conversation to invite them in often works (and then I be darn sure I honour my word with regards to agency).
And if the invite isn't accepted, then I am totally OK with that as well. Certain players prefer different challenge levels. And these aren't fixed either -- tastes and interests in difficulty levels can shift based on a whole host of things, from real life to the campaign world. (And don't use that as a justification to badger or shame someone into a game they will not enjoy.)