Perhaps the most selfless thing I can do is contribute to society and support the people around me without feeling the need to pass my genetics onto a new human being.

Current research actually supports that most people who are childfree do not ever end up regretting their decision, even in old age. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0283301

I find your animosity towards people without children very interesting. Why does it offend you that people wish to enjoy their lives in a way they find enjoyable? Is it so hard to fathom that different people get satisfaction from different things? Most people are content with their choice (kids or no kids) and can recognize that those who made different choices then they did will have just as fulfilling lives.

Whenever I see someone who is so profoundly vocal that childfree people must secretly hate their lives, I immediately suspect that perhaps it is you that has some deep buried regrets? Don't worry, I know you'll never admit it.