Note that some cancers kill you very fast and other kill you in a very long time, so you have a chance of die from another cause.
If the study in a small group proves that the miracle drug is ineffective and moreover it reduces the life expectancy to 1/2, then by not giving it to everyone avoid the nasty effect of reducing the life expectancy of a lot of people.
Of course, this would apply especially to a drug that hasn't been in regular use for 60 plus years.
Side effects of HCQ are well known, and safe dosage has long been established. If it saves some lives, why deny it to patients knocking on death's door?
If the study in a small group proves that the miracle drug is ineffective and moreover it reduces the life expectancy to 1/2, then by not giving it to everyone avoid the nasty effect of reducing the life expectancy of a lot of people.
Take a look at some "miracle" cures of cancer of the past, like https://theincidentaleconomist.com/wordpress/the-rise-and-fa...
Also, since a few years in Prostate Cancer the recommendation is not to treat all cases after detection https://en.wikipedia.org/wiki/Prostate_cancer#Management