Many people also invest the money they would need in the near future. Thus, when the price has gone down, they have to sell it for not to be in much more loss. Eventually, this kind of investment ends up with disappointment and we saw it in the last three years in crypto stuffs.
Yes, it is silly to invest with what is needed soon. It is the pathway to ruin. I know a few who have done this, and are nearly always in debt. Don't invest what you need to eat with.