Remember that in, say, a cancer treatment trial, patients are signing up to potentially not receive the treatment depending on the run-in and randomization phases. I'm not suggesting these patients are forced into that decision; rather, I'm just pointing that controlled, randomized trials have some ethical fuzziness around them.
But until treatments/vaccines were developed, everyone on Earth had the disease-equivalent, sometimes-fatal status of "no prior immunity to COVID".
Sure, the scale is massively different for a young healthy person: "susceptible to COVID" would mean a moderate chance of catching the disease (growing over time), and then a small chance of death or previous complications. But the "susceptibility" is also a "health condition" with nonzero risk-of-death.
And for society as a whole, COVID passed cancer as a cause of death last year, and in January 2021 has been killing about twice as many people as all cancers combined.
So "diagnosed-with-cancer" versus "susceptible-to-COVID" shouldn't be that different in terms of the kinds of risks we'd let informed people take to address that danger.
