Traders are supposed to treat currencies as tools and not something to get attached to. But this differs on the basis of long term or short/mid term. While coins kept for long term purpose will be there for sometime and one may get too attached to them, those in short or mid term have to dealt with quickly and decisively.
In reality what most newbies end up doing is buying or selling at the wrong time and not just make the mistake of getting attached. This is more true when coming to altcoins. Every trader should know that any altcoin needs to be traded quickly as soon as profits are seen and as soon as they break even on ROI.
I would guess that long term ones get attached even less than short term ones if you ask me. The reason for this is that if you are after short term profits that means you need to know everything about a project and make as much profit as you could from it, whereas if you are in the long term part of it then you do not have to do any of it and you could end up making a profit based on just ignoring it for the longest time.
If I get bitcoin and hold it for 10 years, I do not have to look at it at all, just come back once a month maybe and check it and that's fine. You can't do that with short term, you have to be on top of the situation at all times.