If you start from a premise that the measures we implemented in our lockdown were objectively unnecessary, and that somehow this is an agreed fact, then I can see you would start thinking accepting them is a sign of some kind of dangerous irrationality in the population. But that those measures were unnecessary is just some people's view - it's not some kind of objective fact. Lots of people accepted and still accept the measures we've taken, not because someone has told them they should and they've blindly accepted it, but because they can see the implications of a new disease like this and what will happen if it spreads widely.
Yes but a low death rare is contingent in adequate hospital care if necessary.
Boris Johnson is one if the survivors but if the healthcare system had been full and unable to admit him the outcome would have been very different.
This sort of implication, for a start! One of the basic problems that comes along with any pandemic of a novel disease is that it doesn't matter how good our healthcare is, if we don't have enough of whatever it is that makes it good (beds, staff, machines, PPE, meds, ...), then once we have more simultaneous infections than our healthcare can cope with the death rate will go right up. It won't matter that you could have been saved with oxygen or CPAP machines or ventilators or antibiotics, if they've all been used up before you get to the hospital with covid.
You can tell people their individual risk from the illness is low till the cows come home, but you can't make them un-know the fact that with too many cases at once, that hospital treatment won't be available. Or that with too many cases at once, hospital treatment for other things won't be available either. Our individual risks of dying are not the only thing that should be governing our behaviour at the moment.