Nature, and evolution, don't follow motive based logic. Random mutations that are temporarily beneficial but are detrimental to the long term do happen.

To put it another way, a cell mutates based off of random chance. It doesn't have desires. We only have to go back as far as 1918 to see an example of a virus that could not have been engineered and was highly transmissible and highly deadly. As you say, in the long term that doesn't work out- the virus in that case mutated to be much more mild- which is why you won't see viruses like that surviving for long. But it still doesn't make sense to assume viruses evolve according to a motivation based logic.

Obviously the person you’re responding to doesn’t think covid is conscious and has motivations…

> temporarily beneficial

This was the crux of my point.

Then your point makes no sense.

Please work on your reading comprehension and stop being rude.

You're assuming that viruses don't have natural reservoirs. For example, viral hemorrhagic fevers, particularly filovirus VHFs, are both highly transmissible and highly deadly -- accounting for their history of rapid, fast-growing, and quickly-diminishing epidemics amongst humans -- but have stable zoonotic reservoirs that allow them to circulate freely across those populations. (Bats' unique immune system, like camelids, makes them a particularly good evolutionary proving ground for viral evolution, so they serve as a reservoir and a source of ongoing viral mutations.)