Can't lose if you don't sell?

I have my list of selected companies, and i'm looking at the past charts from last year. It seems any given time where there could be a big loss, if you just waited long enough, you would be able to make your gains back if you just check it from time to time. And vast majority of losses i have ever made are from selling the stock. Of course, there are exceptions, but if i keep it diversified, the general return will still be very positive. Why have i ever sold anything? Probably because i was trying to micromanage every position and maximizing returns. But i've been getting tired. It seems like if you just let it run on autopilot, everything would go just fine. It's not like i was expecting the companies would go bankrupt or i could find a better replacement immediately. Suddenly felt dumb for ever trying to micromanage.