... pretty in touch with my never-to-be-fulfilled desire to have a family, and I can imagine that if I were a bit less in touch with how I think about things, I might repress that feeling into hostility toward people who do want to have families.

I don't think it's that all these people are capable of having families financially but choose not to---most of the people my age (early 30s) who have families have one income earner making substantially more than average, and a second income slightly above average. Obviously, not everyone can do that.

There's no point in desiring something that one cannot afford, especially if it's not like it's just a matter of "saving up" like for a stereo or a handbag or something. Most people, if they really want a $1000 handbag can save or buy it on credit...not so with kids.

You have left out choice in your post.
It has to do with the choice not to have kids.
Sure maybe some of it is due to economics or cultural pressure which make people choose unconsciously.
If a person or couple choose consciously both having or not having kids can be very rewarding and lead to a happy life.
All is choice,choose consciously and lead a much more fulfilling life!!!

The Straight reader is young, or thinks they are young.

Therefore, maybe people here are more interested in having sex than thinking about what comes after that

The negative reactions have been to folks telling other people what to do. When it comes to reproduction , that's a POS thing to do, so the votes are warranted.

Also, please refrain from judging the desires of others as natural or unnatural. Variation is the human norm.

Kids are for yuppies, "new Canadians", and people who haven't yet discovered they are no longer middle class, but 21st century serfs to a New World Globalist order.

Stay in Vancouver.
Have Kids.
Work less.

Choose two. At the rate we're going, choose one.

Its because big cities have a lot of culturally leftist elitists who want to maintain their self-centered lives of going to work, and then sipping cocktails, craft beer, or fair trade coffee with organic soy milk with their friends afterwards. There's also squeezing in time for yoga, snowboarding, buying $300 sneakers, and checking out the newest foreign language, independent art-house flick.
Kids get in the way of that.
There's nothing wrong with wanting a life where you focus exclusively on yourself, I just wish the resentful people the OP is talking about would be honest about why they don't want kids. It's the disingenuous prattle about overpopulation, dwindling resources etc., that makes me roll my eyes.
I also think these people direct their vitriol towards people who say they want to have kids because they're perceived as one of those "deplorable" people who might have traditional values. When Vancouver leftists think they've gotten so much as a whiff of someone expressing traditional values such as an affinity for marriage or family, they pounce. Hence, the downvotes and negative comments.

I chose to not have children because I was so severely abused as a child that I doubted my ability to be a good parent. I'm old now - long past being able to conceive - and I don't feel like I've missed out on anything. I have no regrets in this department but rather a deep seated relief that my drunken shenanigans in my youth did not result in an unplanned pregnancy. Ha ha.

People choose whether or not to have kids for a variety of reasons; those reasons are usually complex and rarely have anything to do with being able to afford soy lattes.