Ah yes, I had made the mistake of not looking through the link and so wasn't clear on what was or wasn't included. Thanks for flagging that.

I don't mean to dispute your preferences; I take for granted that different options make sense for different people or for people in different stages of life. However, I've now had this conversation with bicycle advocates a few times, and they always seem to assume that their needs are a close proxy for my needs, and they're not.

Looking through the details of the cost benefit analysis, there's a bunch of factors that aren't obvious that do need to be included.

I've had jobs where there wasn't good transit, and where it wasn't feasible to relocate myself. Much of the United States doesn't have usable transit, and does have bike-unfriendly geography.

If you have to move furniture, yes, you can rent a truck. But if you have two weeks of groceries, or a passenger and a few suitcases, a car is fine, and a bike (even with a trailer) is not fine. Car share isn't a perfect substitute, since often the car-share is a significant distance from where you live, and since it isn't reliably there when you want it. There's real economic value to having the car exactly where you want it, when you want it.

Renting cars for vacation or medium-distance overnight travel can be an option. It isn't included the linked-to calculation and it can get expensive depending on whether you need to keep the car rented for the period in which you aren't actively using it.

Right now, some people own cars and some don't. I'm sure there's some status quo bias and some bias in favor of social convention for owning the car. Beyond that, why do you think people are making this decision irrationally? There's enough car-free folks that I think it's not that hard to see what the benefits and costs of the lifestyle are.