Having an emergency fund can really make all the difference when bad or u expected situations arise, it can save you from going into debt and even panic, an emergency fund is also good as a bitcoin long term investor, it can help you from dipping your hands into your investment prior to the time you planned for it, imagine a situation where your house got burnt or someone got ill, you can depend on your emergency funds to solve those problems.
The concept of emergency funds have long existed in the business but it was not called by that name. It is actually a mechanism for risk management because it helps the investor in managing the investment by eliminating the chances of selling some or all of the investment before the time it was planned to. This is just like an investor not putting all his money into the investor instead putting part while setting some funds aside for other needs such as you highlighted. This is not peculiar to investment in Bitcoin or cryptocurrency but across several sectors, plans must be made for basic needs and other needs that may arise which were not factored into planning and budget.
Personally, I have a fixed percentage of my income I invest in Bitcoin and until I change my strategy, that amount will be constant as I am using the DCA method. While being invested, I understand the importance of living, leisure and rest, so I also make provisions for these because I don't believe in punishing myself now with plan to only enjoy at old age. I have to live life well now, enjoy within my limits, invest and also save for retirement.