Conventional wisdom says have 3-6 months expenses (rent, bills, food, etc) minimum saved up in case something happens. Whether it is a job loss, natural catastrophe, or some other even that you need cash on hand quick, it's always there to rely upon. Most also say not to have it in investments or the like as it could be too tied up at a time when you really need it.
But the access question becomes highly relevant when you extrapolate further. For many esp in western countries, this sum may be in the 5 figure range which is fiat makes a not inconsequential pile. So unless you want to feel like Walter White in Breaking Bad, people will probably want to keep their emergency fund in a digital solution, perhaps in bank to try and earn some interest as well. But what happens if the bank decides to default and keep your money, for any one of many reasons. Either you don't have the exact paperwork, or they can't get it in time, either way ultimately makes it hard to access your wealth.
Enter BTC. I am thinking with thr market as it is now, to convert at least half of my emergency fund into BTC and holding for long term. The rest is in a high yield (lol) 2% APR savings account and there it will stay until I may need it. The BTC will be the first mover of my emergency fund, possibly thr only asset I truly hold and control myself, and if it turns out I don't need all my fund I can convert the fiat back to BTC and restock thr fiat as needed and at leisure. This way I have BTC exposure, an uncensorable asset to deploy if I really need to, and a plan to replenish it should the need ever arise.
I know spending BTC for fiat is not in most ppl's game plans on thus sub, but in any scenario where I need to use my emergency fund it would all really be a FUBAR situation with SHTF and in this scenario is a matter how how quickly you can unfuck a situation, which BTC's global network does.