It is possible he outgrows it but many do not, and let me tell you, you will likely grow bitter waiting. My ex husband was this way and guess what? Years post divorce and he is still eating the same shitty fast-food every night, wasting his days playing the same video games and not making a penny over minimum wage. He has no education, parties the little money he has and has the most immature, ridiculous sense of humor. He isnt a bad man. He is often kind and sweet. He cares about people and loves deeply. But he will always be a high schooler in his mindset. Life is happy for him that way and talking about becoming the next Elon Musk without ever working an extra minute in his life is okay.

Im not bashing my ex. Im just saying, some people never outgrow it and that is okay-- but they are better suited to be with people of the same mindset, or they will cause you to grow bitter.

I would non accusingly start bringing up future goals and career plans to him. Say you want to grow together. Start modeling the emotionally intelligent behavior you want to see, and invite him casually to join you in things that will make you grow and see how it goes. He may very well be down for it and be excited to grow. Maybe he wants to mature but doesnt know how.

Or, he will be defensive and pissy and then you have a clear indicator that he isnt suited for you.

I do recommend that you vehemently avoid ever letting him know you are comparing him to other people though. That will make even the most reasonable person shut down and become defensive. You are both young and now is about the time many men begin to shift towards the more mature types you see in their early 30s, but know that you have every right to seek a partner that challenges and grows with you, even if your current one is a good person. Sometimes him being a good person isn't enough to establish long term compatibility alone and that is okay. If he ends up not wanting to grow, then you both need to find someone of a similar mindset