I would argue that this is not because it was difficult to see coming, but because most people have a bias that makes it difficult for them to imagine something that's "normal" abruptly coming to an end. This was the era of "I got a loan for this house in 10 minutes. I added granite counter tops, mopped the floor, and sold it for a $20k profit in 9 days." type shows.
TV is TV, but that was genuinely happening. The market was just completely broken.
The part of the housing crash that I was inferring was hidden to most was how deep the credit markets were tied up in housing, to the point where a housing bust meant banks collapsed and all money was frozen.
I was young(ish) at the time, but I imagine some knew housing wasn't sustainable. I'm not sure there were many outside the stars of The Big Short quite knew how vulnerable the entire banking system was because of housing before it all came down.
The housing crash was obvious - talk to anyone trying to buy a house in 2004 or even 2003. By 2005 or so I had friends that were getting cold called with offers of nodoc nodown interest only loans.
It wasn’t necessarily obvious that specific banks would fail but it was obvious that the big guys were playing high-risk games and were going to be left with a lot of foreclosures or writing off a lot of paper value. This was known to basically everyone in the industry, too - I briefly considered buying in New Haven in 2008 and got mortgage pre-approvals from a few banks. I had an interesting conversation with an older loan officer at a Connecticut state bank, who was the only one who didn’t approve me for WAY more than I thought reasonable and explained why very matter of factly, and noted that since his bank didn’t resell the mortgages as CDOs they had to be more careful about risk.
TV is TV, but that was genuinely happening. The market was just completely broken.