@Pshop55 Maybe others have said this, but I don't think you can 'miss' something you haven't experienced. So, in that sense, being childfree by choice isn't a case of missing out, it's just a different life - no better or worse, imo. Also, no two people experience parenthood in the same way. It's much harder for some due to a unique combo of personality, genes, health status, personal history and circumstance, than it is for others.
Now that I've had a child, in a thankfully fortunate set of circumstances (planned pregnancy, healthy birth, stable, loving and equal relationship with DD's dad who is a genuine 50/50 parent), I can say that it is undoubtedly the most powerful and profound experience of my life, different to any love I have previously known, and there is no way I could live without it. As a result parenthood has given me more joy, purpose, and satisfaction that anything I previously experienced as a childfree person, but it has also made me far, far more vulnerable. The stakes of my life have changed wildly. But, had I never had a child out of choice, I wouldn't be any the wiser. So, like I said, no better or worse off. Just different. Of course, if a person wants a child and can't have one for any reason, then yes, of course it is entirely valid for them to feel they are missing out and I would have to agree.