In some cases where you have exhausted your discretionary income for bitcoin investment it's not bad if an investor uses little of his emergency fund to purchase bitcoin and still make a replacement back to your emergency fund when things are alright but emergency fund shouldn't serve the purpose of discretionary income using your emergency in a one time purchase of bitcoin doesn't give you a bad method to invest in bitcoin.
It may not always be convenient for an investor to use the emergency fund to buy Bitcoin and then try to make it up again later. When an investor repeatedly uses the money from this fund, he may fail to provide the money from that fund at any time. So, it is better to keep the money from the emergency fund without using it. Yes, in some cases, if there is need. For example, if the price of Bitcoin has suddenly dropped so much, then the emergency fund can be used if there is an opportunity to buy at that time. However, it must be remembered to replenish the money to the emergency fund as soon as possible. If it takes a long time to provide the money from the fund, then it is better not to use that money.
I totally get what you’re saying. The main idea of an emergency fund is that it is supposed to be untouched, because life is unpredictable and you never really know when a real situation will hit. If someone keeps dipping into it just because they see an opportunity in Bitcoin, then at the end of the day when an actual emergency comes up, there’s nothing to fall back on.
And in most cases, they may even be forced to sell off their Bitcoin at a bad price just to fix the problem the fund was originally meant for, which kind of defeats the whole purpose.