I would disagree that it is "not a real question", and have voted to reopen it.
The problem is clearly that the company culture discourages employees from using their PTO, and the OP is asking if he should let company culture influence how much PTO he uses. He also mentioned that he's not from the US (which I think is relevant), and is not sure if any kind of unspoken "rules" about PTO exist in the US.
Personally I've worked in similar environments, and think this is a good question for the site. I actually had the same question when I first started working too. I used to never take my PTO, or when I did it was with some "valid explanation", like going on a week-long vacation. Now I take it whenever I feel I want a day off, or when it's going to expire. :)
I've already voted to reopen it, although when I went to try and edit the title and highlight the actual question just now, I see someone has made a more substantial edit that changes the nature of the question.
If it's determined the edit is too much and gets rolled back, I'll post my changes, but if not I won't bother.
The summary of my changes was to change the title to "My colleagues frown on me for using my vacation days. Should I stop using them so much?", and to clarify in the body a bit more that the OP is not from the US and is looking to find out if there are unspoken rules in the US about taking PTO that he is not aware of.
Edit: I actually was reading through the edit and realized it invalidated too many of the existing answers because of how much it changed the core question. I've rolled back that edit, and applied the one I was going to do.
If the community decides the current phrasing of the question isn't good enough and rolls it back to Chad's edit, I won't complain, however I'd prefer the question as it is now because it doesn't invalidate so many of the existing answers.
Edit #2: I realize why some users were thinking the question was "not-constructive", so edited the question to be Should I let company culture influence how I use my PTO?, which I think is probably the most constructive way we could rephrase the question without losing the OP's original intent.