@James637 in my opinion, if you've got to 30s and have developed many aspects of your life well, the decision would be harder. If you enjoy your job and find it meaningful, have lots of interesting hobbies for example. Having kids would mean sacrificing that other aspects of your life.
It would be easier to make a decision as a 20 years old, when you're just starting out in life and have not actually figure out what you like/you don't like.
I don't agree pp up thread who said that as parents you know both sides, I think once you became parents, your brain would try really hard to justify your decision. You also wouldn't know what life would like without your kids and as the kids are here, your love for them would make you blindsided to other possibilities.
I agreed with you that it is a massive gamble, mainly because you don't know how your kids would turn out. There are people in this world who in my opinion should never be born, if I were their parent I am not sure I could still say I am happy to sacrifice my life to have them because they have given meaning to my life, even though my kids turn out to be horrible people who did bad things to others. But again I think once you became a parent, your unconditional love for them would mean you would love and support them regardless.
If there were a guarantee that my kids will grow up to be amazing, kind and great people then I think that would make decision a lot easier
Many people would not agree but I think that someone who is wise & well rounded should be able to make their life happy, interesting and fulfilling with or without kids. I am not one of them as I want kids, but I know people (older relatives) who have kids and said that they would lead happy and fulfilling life with or without their kids. Life would be different they said but they are confident they would be able to make it interesting and fulfilling even without kids (or with kids and without expensive holidays & less money)