If you follow the "herd" aren't you considered as a stupid investor yourself? Because any investor/trader in their right mind won't let their emotions ran over their decisions because they are seeing the market in the state of panic. This is what separates the real investors from the fake ones as they know what to do during these times and they don't follow the hype, FUD, or anything else that will lead them in a bad position. The real investors also are the ones who are taking advantage of these "stupid investors" as they are the ones who are buying and selling their mistakes.
I don't know if you can call them stupid, maybe irrational at times, How many have we seen buying at the top price and easily burned when the bearish trend suddenly take over and the herds are never to be found around the corner? That's the sad part for those investors (usually newbies) who jumped in and thinking that we can go parabolic forever. Common sense will dictate that it will not the case so unfortunately for them once they enter the whole picture suddenly changes. I'm sure that they all learn their lesson in a very expensive way. And I don't think they realized what really happen until they sold everything to cut their losses.
Of course buying low and selling high sounds like a great plan, until you actually try to execute it. This requires an in-depth understanding of the mechanics of the market, something most people simply aren't willing to put the time into uncovering. Simply holding has done well for the last few years, but obviously isn't the optimal way to grow your investment.
Exactly. The old adage has been preached million times but there are still investors who are tempted to sell at the smell of every dip. As much as we want them to HODL, they do the opposite. Well, its not that easy though, really take years of practice not to be affected by a sudden dip or even a major crash.