Viruses that almost always hospitalize or kill people are actually easier to contain. (“Hey, whoa, that guy is bleeding from his eyes. He’s coughing like crazy and bleeding from his eyes. Please don’t let him into choir practice thx!”)
At the other end of the spectrum, the viruses that almost never hospitalize or kill people are similarly easy to let go. It’s just a cold. You can still come to work. (If you care enough about corporate profit to infect your coworkers?)
But, so … this one lets most people go. While also critically sickening or killing tens of millions.
(I realize I’m ascribing agency to the virus. It’s not even alive. That’s just a metaphorical thing. It’s a force of nature.)
Point being: The fact that this virus usually doesn’t kill people is also exactly why it’s killed millions of people.