A long term investor who lets winning positions run, but cut losses before they grow will surely reduce losses, and have a profitable investing account.
Imagine one opens ten bullish positions as a long term investor. Moreover, one is also a defensive investor that hates to lose.
If one closes six positions in a timely fashion because one realises that they are more likely to cause greater losses, but one also maximises the gains of the other four positions, one can still be profitable.
The idea is to cut genuine losses, and double up on winning investments. Of course, one requires more experiences and skills to turn a risky investment portfolio into profit.