Now coming to why you should form an emergency fund and what is its use, basically so that your investment is not irregular, that is why many investors form an emergency fund. The use of an emergency fund is when you have a financial crisis, but your investment may be irregular, so that an investor's Bitcoin investment is not irregular during a financial crisis, that is why those investors form an emergency fund with their own extra money and use it later.
Once an emergency fund is used, when the financial situation of the person is normal, then the amount of money that he took from the emergency fund and invested in Bitcoin can be added back to the emergency fund. This way, every investor will not have the possibility of irregular investment. Since I have used an emergency fund, I know that this is a really effective strategy for investing in Bitcoin consistently.
In fact, even if you don't invest in Bitcoin, it's important to create an emergency fund. Emergency funds are created for urgent needs, you may get sick at any moment and you will need money if you are sick, so if you have emergency funds it will not affect your investment. Maybe some investors reserve emergency funds to maintain regular investments, but it seems most investors reserve emergency funds for urgent needs. I personally reserve emergency funds for urgent needs, I do not reserve emergency funds to maintain continuity in investment. I will never buy bitcoins using emergency funds, because investing consistently in bitcoins is not mandatory.
Sure, many people have tried to ignore the advantages of saving money for emergencies because life may be unpredictable, as you said, sickness or other unexpected things can happen at any time, and if you already have an emergency fund, you will not need to touch your holdings; if you use this strategy, your investment plans will not be affected with other needs.
Of course, emergency funds should not be used for buying Bitcoin or other investments. The target of that money is to make you comfortable whenever you have an emergency, not to be pursuing quick money. Investing should be done with spare funds, not money we might need tomorrow, that is why it is important to keep your emergency savings aside from investment funds, which allows you to be consistent and avoid unnecessary risk.