This. Even if you could buy the house outright for cash, it still would have made sense to get one of those mortgages, base on that (reasonable even at the time) expectation that risk free rates would swamp that value soon enough, and, no surprise, here we are!

I was pondering that tradeoff myself two years ago, having retired early from crypto. The only issue is, to get the 2.5% you had to show Fannie Mae-acceptable regular income. Which is still possible: the FIRE people have a system for putting your money in a trust that pays it right back to you[1], then waiting two months to establish a history, and then you dissolve the trust once the mortgage is finalized and you've closed and moved in.

I would have done that myself except that it would involve putting a big delay on my search. Early comment about it: https://news.ycombinator.com/item?id=31000286

[1] https://old.reddit.com/r/fatFIRE/comments/ojs18l/obtaining_a...