It literally is possible because there is a modern society with replacement fertility- Israel. And even if Israel didn't exist, it would still be literally possible because there is no law of physics against it.I said this before - it's literally impossible for a modern society to reach replacement fertility. It's not just a money issue - I am financially comfortable but I will never ever consider more than two kids because kids are absolutely exhausting and take up all your spare time. As a responsible parent, you just need to sink X hours into each kid each week, and there's a minimum value for that X that money can't solve. And there's basically no personal or practical benefit to having more than 2 kids.
Like I said, it's a subjective question of values. According to some people such as yourself, it's "exhausting" with "no benefit". In that case, you'll leave no descendants on earth. According to other people, it's worth it for many reasons that they could give which are valid to them. Those people WILL pass on their genes. So basically the people who do value children as a cultural matter will inherit the earth.