You've got the down payment covered — it's just in BTC instead of a checking account. You find the house, you start the mortgage application, and somewhere around the asset-verification stage your loan officer says the words: "You'll need to sell that and let the funds season for 60 to 90 days before we can use them."
Now your timeline is blown, you've been forced into a taxable event months before you needed one, and you're holding a pile of cash through whatever the market decides to do next. The house you wanted? Someone else closed on it.
This happens for one reason: underwriters must verify that down payment funds are really yours — not borrowed, not gifted without documentation, not illicit. When money shows up in your bank account and the underwriter can't tell where it came from, the fallback rule is time: if it's been sitting in your account for two statement cycles (typically 60 days, sometimes 90), they stop asking where it came from. Seasoning isn't the requirement. It's the absence-of-documentation penalty.