altrego99 is expressing a considered personal view with which you disagree, not insulting you or the mass of humanity. You are entitled to your personal view as well. But you could recognize consideration of the issue as a good thing and the disagreement as normal and healthy. Instead, you are calling people terrible names and picking on grammar, without provocation. Please don't continue in that vein.

I think for most people, you are right that having a kid is a fulfilling thing. I am personally glad that someone is having kids (particularly if they are doing a good and thoughtful job of caring for them). But the implication that no one with kids could ever disagree with you is not correct - though it is unlikely that they will bother to do so in public. I have talked to several people who do regret having kids (particularly in a certain time or situation) but they are not so likely to say it - both because of the kind of aggressive reply you have given but maybe also because they are likely to be wrongly taken as saying that they do not love their children, or that they wish the child did not exist. A person can believe that having kids is not necessarily altruistic, or that there is no moral or practical imperative to have kids, without being an awful arrogant psychopath.

Before you have a child, there is no child to wish the nonexistence of. And since it is an irreversible long-term decision, you should definitely think about the pros and cons in a rational way. Many people do come to parenthood by a reasonable, conscious choice and that is a blessing. Other people decide not to. If that is in their best interests then good for them. Perhaps there will be a future time where it does make sense to have kids. Leave them be. It's a personal decision, not a moral necessity.

Not everyone has to get married, either; not getting married doesn't make you a psychopath or a pathetic unfulfilled person, even if it's a nice thing and a great life work for many people.

You enjoy all of those things to gain the capacity to enrich the life of your child.

I'm unconvinced. There are many worthy things in life; children among them. Doesn't mean your life is worthless if you don't have them.

The comment you're responding to raises perfectly valid points. Sorry, but in my experience having children does not change your life into a love-fest revolving around them. You miss out on a lot of perfectly fulfilling hobbies and a lot of time. There are upsides, but it may or may not be worth it to you. I think deciding against it may be a better and happier option for many people. You can't just count on the experience of those such as you who are apparently so happy to be a parent that it makes you angry at those who suggest it might be otherwise.

Now what, are you going to call me a psychopath?

For some people, having children is not worth it. For others, having children is.

Every person that has ever entered into the "mass of mediocrity that is humanity" was born at some point and, as the mass of mediocrity is by definition what most people will end up being (by your own words) a part of then why add to it when one does not desire to do so?