It's not obvious to me.
As an example, lets say hospitals have a capacity of 100, 40 of the capacity is generally taken up by non-lifestyle factors, 40 is taken up by various lifestyle factors (things that could have reasonably been avoided from a better diet, exercise, or otherwise), and the remainder is left as buffer. Now, lets say covid takes up 25 capacity, which now overflows hospitals by demanding 105 capacity. Why is this new lifestyle factor (not getting a vaccine) obviously worse than the previously accepted and accounted for lifestyle factors?
Is it the ease of avoidance? 3 jabs and you're done? If so, what about the injuries we accept that could be avoided entirely through inaction (sports, motorcycles, whatever)?
Is it the magnitude? Looking at covid as a single factor, it could be argued that it has far greater impact than any other individual lifestyle factor. but that information sure hasn't come up in any discussion I've seen. It's always left as an exercise for the reader.
Is it the suddenness? Covid sure has been a shock to the system that it was unprepared for, but that's only true through the lens of comparing pre-pandemic to current moment. Looking at the current state, it's no longer sudden. The existence of covid is now known, and so is hospitalization needs. Now it's just a question of capacity, not suddenness.
I'm not saying the point can't be argued, but it's certainly not obvious to me. And if every discussion is left as "it's obvious, why can't you see it", the discussion won't go anywhere.