Until my late 30s, I always sort of assumed I'd probably have children "someday", but honestly, I was never really driven to have them, and for one reason or another, we never have.
I can still imagine happy snapshots of how our life could have been with children, but life can be just as good (if not better, in some ways) without them. (And there are many times I find myself grateful to not have to deal with the headaches and uncertainties that come with parenting.)
I think many people have children just because it's "what you do". For most, it works out well enough. Once you have children, they understandably become your life and you can't imagine life without them.
But if you don't have children, all the time and effort that goes into raising them can be diverted into other pursuits. You have more disposable income, more time, more freedom and flexibility. There are options available to you than you are all but impossible with children to consider.
I can't deny that there are still times when I wonder about what we might be missing and question what the future will be like without children (and potentially grandchildren), but I've seen others live very happy and fulfilled lives without them, so I'm confident we can, too.
I think it's important to remember that no-one's life is perfect. Some people have children and end up regretting the decision. Even people who love their kids and seem to be living a perfect life have worries and problems related to the children. What they put up on Instagram is (usually) just the best, brightest, funniest, most exciting aspects of parenthood. They tend not to focus on the hard work, concerns, frustration, and sheer boredom.