I think a lot more people than are willing to admit feel the same way, OP.
For the majority of my life, I've never truly wanted children. I recently underwent a spell of questioning and doubt over my child-free status, following the arrival of my dear nephew. After much reflection, I realised that I was simply getting caught up in the excitement of it all and that it was one thing to be an auntie and entirely another being a parent.
I simply never had the maternal instinct or drive. I was never the sort to look at babies and get the warm, fuzzy feelings. It just wasn't there. I knew I didn't want kids, I suspect, in the same way that some people just know that they do want kids. It's just something that is either there or it isn't and I decided that I wasn't going to try and force it to be there.
During my brief spell of "wanting children" I realised that was what I was doing. I was forcing myself to want them because everyone around me was so desperate for me to want them and have them. I didn't, and I would walk around with a knot of dread in my stomach at the prospect of what I was leading myself into.
As soon as my DP admitted that he didn't want children, the knot disappeared and all I felt was relief. I'd been let off the hook. For me, I took the view that if I wasn't 100% in, I had to be 100% out. No child should be subject to half-arsed parenting and a parent who isn't fully engaged.
There's no way to know for certain if anyone would truly be happier if they made a different choice in life. Everyone has those "what if" moments. We can only make the best choices for us based on the information available to us at the time. Your life would be different without kids-but there'd still be struggles. There'd still be responsibilities and drudgery. Just different ones.
I honestly believe that even though you know going into parenting that it is going to be hard-no one can prepare you for just how tough it really is. It's not until you're in the thick of it do you truly appreciate that and I suspect it's tough in ways that no one prepares anyone for as well.
I still think a lot of people have children because "that's just what you do," and don't give the alternative a single thought. I have read numerous stories of people who did just that and went on to regret it. Which is why I think these kinds of conversations are important-so people who are maybe sitting on the fence or who don't know can really think about if it's for them or not.