A lot of people in the US who bought shortly before the US housing crash in 2008 paid a lot more money than what they can sell for. Sometimes they can't even get half.
This is plain false. I would love a zillow link to show one single example of a house in 2008 being worth more than it is today. Housing in most of the US is up 20-40 % in the last two years alone and the crash in 2008 was around 20-40%.
This is trivially easy: this home was sold in 2007 for 2.9m and was just recently solid for 1.8m 7 months ago. Top of market took a huge beating in 2007-2008.
I'd start by looking at places that had huge real estate bubbles like Las Vegas or are far enough away from anything interesting (like all the shitty Bay Area suburbs).
For a lot of not great reasons I've a condo in one of those shitty Bay Area suburbs. Four units in this complex were listed for sale this year. Two sold for a bit under 500k, and two are still asking well over 500. So yeah I'd say the upper bound currently is $500k. Pre-COVID prices were in the low 400s.
I've checked out the property tax bills for my neighbors, and, yes, some have an assessed value of well over $500k. They've been underwater for about a decade.