On a practical matter, a sudden drop in the value of bitcoin could make it literally impossible to by, as the resulting drop in hash power could mean that no new block is ever mined, so the bitcoin transaction giving you ownership is never proccessed.
In the long run, as long as even a single person has an interesting in mining, a new block will be mined (on average) every ten minutes.
We recently saw a 50% drop in hashrate. Bitcoin kept on producing blocks. https://www.theblockcrypto.com/post/109315/bitcoin-hashrate-...
Further, as miners turn their machines off, even before a difficulty adjustment, it becomes profitable (in btc terms) for those of us with ancient machines to resume mining. Our unprofitable machines suddenly become profitable.
> On a practical matter, a sudden drop in the value of bitcoin could make it literally impossible to buy.
Nope. Most buying happens on exchanges. The flood of liquidity wouldn't suddenly evaporate. And blocks would still be produced as explained above.
Btw. We've had ~90% drops in ₿ price before. https://twitter.com/ChartsBtc/status/1418395476190064645?s=1...