There are two different strategies: buying when everybody is panic selling and buying just in the beginning of great FOMO. Both are working good imho - you just need some experience to catch the right moments in both cases.
The problem is that it is impossible to know beforehand where are those levels and at some point you are going to fail in your prediction and the next question that comes up is what would you do in that situation? This is a very difficult situation to find yourself in but if you are an experimented investor then you can overcome it, but for the newbie traders that are just starting out their carers this is a terrible scenario in which to find themselves in, and many times they make mistakes which compromise their account and they can never recover from them.