that is an illogical reason to hold onto anything. The past is...

that is an illogical reason to hold onto anything. The past is the past and you should try to not get attached or to chase losses.  If you in the red or in the green the only thing that should determine if you hold or sell should be what you think will happen in the future. 

This is one of the first good tips I learned when I first started and it makes a lot of sense. 

The same rule can also apply to many other things... Including romantic relationships, if you think it's not going to be good in the future then you should cut and run, regardless of past memories.

IMO of course