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.
The crisis with the housing criss wasn't that housing collapsed, it's that the world economy went along with it.