While every investors does need an emergency fund available for obvious reasons, you don't have to save up for emergency before you start investing, you can start with your investment first and then start saving for emergency situations later or you can do them simultaneously, and both funds should come from your discretionary funds so as to not disturb your necessary and basic expenses.
Emergency funds are like a fail-safe that helps to ensure your investment isn't disturbed during accumulation, it also makes provisions for situations like you losing your job, it helps keep an investor going until they secure another job and get their income flowing again all while keeping their investment intact.
I'm sure there are situations where investors had to sell the bitcoin stash early to take care of emergencies, it could be an accident and your insurance isn't coming early enough or it's not able to cover your expenses, it could also be a serious health condition that requires alot of money to treat, your emergency income accounts for and helps take care of these situations.
In this case, people's choices may vary. Some prefer to set up an emergency fund before they invest, but there are also those who immediately choose to invest and save up for their emergency fund while at it. However, this should not be an obstacle for someone to start investing in Bitcoin, because they can also invest in Bitcoin even before having an emergency fund. But they need to create an emergency fund as soon as possible because they just don't know when the situation will become unfavorable to them—having an emergency fund will greatly help them face unexpected situations without having to sell bitcoin at the wrong time.
But when people can prepare their emergency fund while they invest, that will be better so when they meet an urgent situation, they can use that fund without disturbing the invest money. Most people are not ready when they get an urgent situation because they don't prepare the fund and use the money in their hand. So many of them used their saving including their Bitcoin investment but we can not blame them because if we are in the same situation, perhaps we will do the same like them. It is why money management is really important for all people to know which place they need to allocate including preparing emergency fund so that will not disturb the other needs.