REALITIES
“Why are many single men over 30 not interested in women?”

It’s not that they’re not interested. They still are.
But they have better standards now.
From what I learned in my career, men over the age of 30 stopped caring about how hot a woman was. They realize that they need a woman that “has substance” as they say. Of course, if the woman in question is also pretty on top of that, it’s simply counted as a bonus for them.
Men over 30 prioritize what their future will look like. They will rather marry a woman who can take care of a family, can look after him and his children, who he can protect and provide for and help him be a better man.
So it’s likely they aren’t enticed by a pretty woman right away.
They are still interested but they want marriageable women now.