Maybe It's because they don't try to look attractive, or maybe they have a feeling in deep that they are judged by another person or what others think about him. I think this is the reason why men don't care too much about what they wear.
And another thing can happen that maybe they are too lazy that's why they don't like shopping or wearing nice clothes because It takes time to dress-up.
It may be because women are more judged based on their appearance than men are. There is There is also some suspicion involved when a man seems overly concerned with his appearance. Men that are very into fashion are usually either labeled as being metrosexual. It may even be assumed that the person.
Typical menswear is driven by tradition, whereas women’s fashion is more versatile and interesting. Men are typically more conservative than women, and this is especially true in professional settings. Also, men's fashion is much less complicated than it's the female counterpart.