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.
An investor without an emergency and backup fund will find it very difficult to invest for a long-term, therefore it is important to have your emergency funds, not necessarily very huge amount in as much as it can meet up your needs when the need arises for it, its an extra fund, which you need to save within 3-4 months so that it can save your investment from being sold off before the time that you wish to sell it within your long-term journey.
Many people save some money before starting to invest, while many do not. So, you earn $200 per month and after deducting all your expenses, you have $50 left to invest. But you do not have an emergency fund. In addition to investing, you need to create an emergency fund. In that case, you can invest $25 and keep $25 for the emergency fund. And what if you reduce your extra expenses and keep them for the emergency fund or invest. For example, eating out at extra restaurants, smoking too many cigarettes, etc., you can reduce all these extra expenses and put money in the emergency fund. In this way, you can very well fulfill the amount of money you want to put in the emergency fund. Try to put 3 times your stable income in the emergency fund. When you are able to create an emergency fund, you can create different types of reserve funds if you want. It is completely up to you. For example, if you have a son or daughter, you need to pay for their education expenses. You can create some reserve funds to meet such financial risks.
You just need to have a good money management skills to be able to invest in Bitcoin because even though you have a source of income, if you cannot manage your finances properly, you may be caught in a very difficult situation in the future which might result in you tempering with your holdings, that's why a good money management skills is required in Bitcoin investment, so that from the little you are earning either weekly or monthly you can still keep your emergency funds out of it, and possibly a reserve funds, because in other to be able to hold successfully and on the longer term, all these needs to be in place, so that you wouldn't have to temper with your holdings if a serious emergency situation arise in the future.