why are men supposed to feel lucky that they don't have a biological clock? why is this a blessing?

It doesn't really matter. Maybe if we were polygamous it would, but since we are monogamous, men and women are supposed to be partners in rearing children and creating a family. So men are limited by women's biological clock. But in a society where men can procreate freely then they can increase reproductivity.. . But in such a society, many males ("betas") wouldn't get the chance to procreate at all, while all women would. so it really isn't a blessing at all. Men need women to procreate, and so you're just as limited by our "clock" as we are if not more because women are the gatekeepers.

I think a lot of women feel pressured into having children before they are ready for them. A possibly sensible time for a woman to have a child would be in her mid-thirties, when she has established life goals. But to have a first child in your mid-thirties is considered quite risky.

It's just another way that women make it look like men have everything so much easier. Just another example of the martyr syndrome.