Not wanting to have kids is not selfish at all, don't know why so many people are making it sound like it is. Having kids you don't want and then not taking proper care of them would be selfish.
I think its as simple as many parents think people that don't have kids are just 100% hedonists focused on themselves at all times and that's why they choose to not have kids. Even that I have a hard time as labeling as any more selfish than the average Joe/Jane since I hold a hedonistic view of human nature.
Some of it is probably also envy as child free people do have more free time and disposable income (than parents with equivalent jobs) obviously. I'm sure social media amps that up as well as I defintely see the childfree couples on our feed (including us) sharing vacation pics, nice dinner/event pics etc. much more regularly than the parents.
My fiancée and I are firmly in the No-Kids Camp. And it's really simple, honestly. It's not about "not adding another life to a dying planet" or "we're not meant to be parents" or whatever. It's just that, when we look at our lives down the line, the path without kids looks more interesting and fulfilling to us.
Kids are great, and if you've got 'em, kudos to you for doing the heavy lifting to keep society on track. That's dope, and I'm happy that there's another generation down the line to pay taxes when I'm old and dusty. But we only get one life, and I'm gonna live mine the way I want to. And I have a wonderful life partner who feels the same. It's awesome.
Good for you guys! That's very much my fiance and I as well. No deep thought ever went into it for either of us. We simply never remotely wanted kids, never had any second thoughts (I'm 38, she's 33), never liked being around other's kids, nor ever felt that we'd be missing out on anything we'd enjoy by being parents.
Like you, we much more enjoy our vision of the future with more free time and more money to live a higher class lifestyle than we could with kids. To live in convenient, walkable parts of the city, eat good food and drink good beer and wine whenever we want, travel the world etc. etc.
As above, many parents have different views and wouldn't trade their lives for anything, and that's absolutely fine. Different strokes for different folks. The only issue us childfree have is when they give condescending remarks of "you'll change your mind eventually," or "you'll regret never having kids when you're old," or viewing childfree people as selfish as they find joy in life differently than they do (which as above I think stems from envy at times on their part).