The problem is the high number of infections. The virus is having a run in a population that has no immunity, unlike a flu. So it is spreading fast and in large

The problem is the high number of infections. The virus is having a run in a population that has no immunity, unlike a flu. So it is spreading fast and in large numbers. A tiny hospitalisation rate multiplied by a very large number of people infected may be more than the hospital capacity. Which is why both of these statement can be true at the same time: this thing is no more dangerous than the flu to an individual if you get it, but it can kill many more people than the flu because the population doesn't have any immunity and many more people will get it.