The human race needs to reproduce in order to maintain its existence. Therefore, people who are having sex and procreating are deemed to be doing right for its benefit. Plus sex has a lot of stigma and sacred sentiment attached to it, so it is seen as something meaningful and amazing; something people only wish to grant you if you are attractive enough. Thirdly, it feels amazing, so the opinion is that if virgins aren't getting it, then they are missing out and there may be something 'wrong' with them.
Notice though that I wrote 'wrong' in inverted commas, because in truth, if you are a virgin, there is absolutely nothing wrong with it at all. You have your reasons, and any decent human being woukd respect you for having them.
The people who mock and ridicule virgins are basically very insecure in themselves for some reason, so they look for a supposed weakness in another person to draw attention to. It diverts attention from their own shortcomings and insecurities.
What I would say to you (because I'm guessing that you feel bad about yourself for being one) is to silently praise yourself just for being who you are. Tell yourself again and again, " I am truly good enough, " " I am worthwhile, " " I approve of myself, " " I feel good about myself. "
You don't need to justify yourself to anyone but yourself. You are perfectly fine as you are. By affirming your own self worth in this way, you will find that it sinks down into your subconscience, and these thoughts are then recycled as behaviour patterns, feelings about yourself, and better self-confidence. When you can develop self confidence like this, you will find that others then treat you better, and you sparkle with a kind of self-worth which feels really good.