No one (serious) disputes this, and the number of cases in China and South Korea is already on the way down. The question is how many people it will kill along the way.
> only those with immune system problems are at risk
1. What immune system problem did Wenliang Li have? (If you want to say "mostly," sure, but "only" is an unsubstantiated claim.)
2. People can become asymptomatic carriers pretty easily. That's a good reason why someone with authority over groups of people that contain some at-risk folks should attempt to prevent or reduce the frequency of such gatherings, at least until we develop collective immunity or a vaccine. (Such people include CEOs, pastors, concert organizers, politicians, etc.) Furthermore, asymptomatic carriers can pass the virus onto other asymptomatic carriers, so until we've started developing some immunity, it's a good idea for even groups of entirely not-at-risk people to limit gatherings, to reduce secondary transmission to at-risk people.
People with immune system problems aren't doomed to die immediately, and it's worth taking steps to prevent them from getting infected, if you can. (Yes, people with immune system problems, older people, etc. have some chance of dying soon anyway. But everyone is going to die at some point. It is a widely-accepted moral principle that this doesn't excuse causing people to die early.)
> secondary bacterial infection sets in, commonly known as pneumonia
This is incorrect - SARS-CoV-2 is unusual in that it's capable of causing pneumonia on its own, without a secondary bacterial infection. Antibiotics won't help. See, for instance, https://www.who.int/emergencies/diseases/novel-coronavirus-2... .
> Overall, the threat that this virus poses to most people and society in general has been overblown by the for-profit media.
What's the profit angle here? What's the benefit to big media from people being unwilling to attend movies and concerts?
Meanwhile, how do you explain the absolute terror in the voices of medical professionals unaffiliated with the media, such as https://twitter.com/tina_nguyen/status/1238879814863519744 or https://left.it/2020/03/13/covid_19-open-letter-from-italy-t... (or, you know, Wenliang Li)?