Focusing on body parts making a man is counter productive, so that's the first thing you need to try and address.
Not all cis men have a penis. Some have a tiny penis. And some men suffer from gynecomastia.
Yup, that's right. Some men don't have a penis, or have a tiny penis, and some men have boobs, and they're not all trans. And I know you'll hit back with how they're a minority but here's a question to ask yourself: If a soldier lost his genitalia in an IED explosion, would you dare call him a woman because of that? That's more of a man than many of us could even dream of being and I'd just dare some loser to call them less of a man because of an injury.
I studied medicine and I can tell you that these problems absolutely do exist. And just like when you were skeptical about a lot of men having fertility problems; men having boobs or lacking genitalia is not something men will exactly share with other men, but they often do seek medical attention! There's only one cis male I know in person who has personally shared with me that he injured his penis in a childhood accident (climbing a sharp pointed fence) and doesn't have much to show today because of it. Otherwise there could be plenty of folks who either have a very small penis, or perhaps none. Maybe they're inter-sex? Who knows? It's not something one advertises to the world normally.
I've said it before and I'll say it again here. The brain is what makes the man, not the body. Does that mean we won't get dysphoric? Hell no! Everyone just wants to be normal but I try to think of my dysphoria as being similar to cis men suffering gynecomastia or who lost their penis through injury. That's what helps me keep my dysphoria in check. If I think that even cis males can feel this level of dysphoria it makes me feel more of a man than less. I'm dysphoric BECAUSE I'm a man, so how can that be faking? That's my logic at least.