It definitely applies to all people calling themselves traders, but not so much (at least in my opinion) to people investing in Bitcoin for the very long term, because as long as you don't sell your coins you won't lose anything.

Losses on paper are part of every form of investment and should always be disregarded. In the same way profits on paper doesn't mean you actually made any profit, because you only profit when you sell your coins at a higher price.

You got the trading part right, but maybe it's a good idea to include in OP that you as investor only lose when you sell at a lower price, because trading and longer term investing is not exactly the same.