Emergency fund is not recommended for investing in bitcoin but no bad to use it because put emergency fund in bitcoin have potential in the future price keep increasing than hold in pocket only, not really difficult for withdrawing emergency fund when saving in Bitcoin due put or hold in exchange wallet.
This is a wrong way to go about emergency funds, emergency funds shouldn't compulsory be in bitcoin but fiat, so that it will be very easy to have access to. Any funds that has been used to buy bitcoin should always be in bitcoin. It is not a good practice to leave funds in exchange which shows that you want to gamble with your emergency funds, which should be properly kept. What is the price of bitcoin drops drastically, it means that your emergency funds in bitcoin will depreciate, another worst scenario is that if the excahnge in which you keep the funds crash, this will be the biggest regret, because you will end up selling your bitcoin at a price that is not of your will. Remember we are looking at how it will be possible for one to hodli for 10yrs without selling a dime from your bitcoin.
my opinion better put emergency fund in bitcoin investment
The only time that is is wise to use emergency funds for bitcoin is when the emergency dunds has pilles up to an extent that, you know that no matter the level of emergency that occurs there is more than enough to take of it. You can then use some part of youe emergency funds to invest in bitcoin. It is also not a most that we will have emergency all the time.