If you are buying it to USE then it does not matter how much it drops. Any drop is merely notional and remains on paper only – until (if?) you ever want to sell it. The only time this does matter is if you are taking out a large mortgage, where obviously, a significant fall could result in negative equity which is not a happy situation. If buying for cash – or mostly cash – a short/medium term further fall in notional value is not really relevant.