That's a pretty unfair characterization of the situation.

1. Rates had been low for quite awhile. Will the rate eventually go up? Of course! But people can only guess when.

2. We're required to consider the possibility of rates going up (the stress test), but I'd thought that for some borrowers we're already past what they were stress tested against.

3. For many, this period of low rates felt like their last chance to get their foot in the door. Whether rates went up or not, it was looking like the barrier to entry (either price or mortgage eligibility) were going up one way or another. You either wait and risk never being able to buy a home (or at least not in the location you want), or buy and risk rates going up. Might some people lose that gamble? Yeah. Pretty easy to understand why they took it though

without considering the possibility that interest rates would go up

More likely they did consider it, but when the BoC explicitly stated that they would not raise rates...

Many people bought homes they could afford, that they needed to live in, after passing a very conservative stress test because that was the way you are supposed to buy a home. Nobody expected the interest rates to more than double in a couple of years. It’s unprecedented. Nobody expected our government to do absolutely nothing about inflation and leave it all to the BoC to fix. You are vilifying and generalizing an entire class of people, most of whom do not fall under the cherry picked description you offered.

Repeat after me: most homeowners are regular people who borrowed responsibly under stringent criteria when they bought their homes.