A lot of long term investors use moving averages - especially 30 week and 50 day. It’s no coincidence that a stock will sell off on heavy volume once it undercuts one of these.
Many also use an anchored VWAP from their initial investment, or the IPO, to decide on what the best average price to add to their position is.
As for Microsoft going down - Everything did - The entire market crashed. A simple moving average sell rule would’ve locked in the majority of gains vs unnecessarily losing it all to a market crash.