Elon Musk

[strife]

You nailed it. You don't lose until you sell. So hold.

Kind of...  

I always try to look at my investments as... If I had the $ that the investment is worth and not the investment... would I buy that investment right now. If I wouldn't, then you should sell it and move on.  

The ideology that you don't lose until you sell is for people who don't want to take the ego hit that they lost money.  If you put $100 into a stock, it loses $20 value for 6 months and then goes back up to $100... did you lose money?  Yes you did... you lost 6 months of potential growth somewhere else. 

If you put $100 into a stock and it goes down to $80 and there is another stock that you think will outperform it in the future... you should sell that stock and buy the other... regardless whether you "lost money" or not.    Sitting and holding a stock that you think will be outperformed by other stocks just because you don't want to "lose money" is silly.  Your money should be in whatever you think has the best opportunity to grow(with risk considered) regardless of what you bought into it for originally.