Why do guys only wanna parent when it’s convenient to them??

I’m sooo pissed with my boyfriend he only wants to parent when it’s convenient for him. As soon as it conflicts with what he wants he doesn’t do shit. He leaves the house whenever he pleases even when it’s late and I need help. He’s so lazy and selfish. He has no ability to truly put our child’s needs above his own. Cause he knows at the end of the day imma make sure our son is okay. So he lets it all fall on me all the time. I’m so tired of it I’m fed up. He could never handle what I do and he’s admitted that but that doesn’t change the way he acts. It makes me wanna just leave him and do it all on my own cause that’s what it feels like anyway. But I don’t really want that. I just want him to help more and parent more. It’s so frustrating how the solution is right in front of his face and he still won’t do anything. Like when will he grow up and mature? He’s 22 I’m 23 he still goes and smokes with his friends every single day for sometimes hours. When he is home he’s mostly on his phone or sleeping. He never cleans up after himself. Literally his only contributions to the household is paying rent. Which is great but sir u NEED to do more. As a mom we do soo much even when we are tired, hungry, in pain, etc. cause we have to. It sucks that he will never understand that feeling.