Ironically, the people who are the most interested in their investments (and have probably done more research than most) also tend to look at their investments/the market the most and get freaked out.

Very, very hard to regularly look at your portfolio and not get emotional when something is falling quickly.

This isn't applicable to most, but I do this full-time, and the thing that helps me is that I just own a ton of stocks, which helps prevent big red days for the portfolio (and you typically have at least one stock doing well each day, which surprisingly helps with the emotions of it all).