Why so many predictions go wrong? In my humble opinion it is because many people fail to understand that complex systems are complex. Namely, there are many variables which can influence the outcome and the relationships between those variables are often not trivial.
In case of predictions for the COVID-19 epidemics, we can't be completely sure how well the social distancing measures will work before they are implemented. We need data, we need some time to observe how the things change after the social distancing measures are implemented. Afterwards we can make a reasonable extrapolations, but they are usually just that - an extrapolation under assumption that things will continue to happen as they are now. In physics such assumption is obvious and justifiable, but social reality might change simply because we made some kind of prediction.
Another excellent point given in the video below by Wisecrack, is that there are two kinds of experts making predictions: foxes and hedgehogs. Foxes are often scientists, who try to be as transparent (explicit about the assumptions they make), open to new data and evidence (which can falsify some of previously held assumptions) as they can. Foxes are prone to changing their mind as they learn from their prior mistakes. Most of the people ignore transparency (because they can't understand assumptions made by a fox) and only notice that such experts often change their opinions. Public appears to favor experts who are adamant about their predictions, because the predictions are often bold and dramatic, yet often backed only by a belief. These experts are known as hedgehogs.
In Lithuania we have a lot of free markets hedgehogs, who often suggest "letting it work" ("laissez faire") as being solution to every imaginable problem. While free markets are solutions to some problems, they are definitely not a solution for all the problems, as free markets are based on theoretical model, which works only when certain assumptions are satisfied (check out our previous series of post on price formation).
So, without any further side points, we invite you to watch a video on Wisecrack. It covers much more than we have written about in the text above.