You should never buy BTC with emergency funds. Many people see the market fall and aggressively use the emergency funds they have at that time, which is completely wrong. Emergency funds are created to deal with unexpected financial disasters. If you invest with your emergency fund at that time, if an unexpected financial disaster comes, then you have no choice but to sell your holdings. In some cases, you can invest with emergency funds.
You make a lot of sense here but I have come to think of it in different perspectives even after asking some questions about how these funds need to be spent. Here I see more vital details why many investors are failing and need to make proper plans so they don't end to investing and coming back to sell part of their investment because they used the wrong fund for investment.
Crypto investment is not something that is going to be profitable immediately, most times it takes a lot of patience and understanding before we can hit our chest that we have made some good profits from the market. I know they're quick investors who only come to take their small profit and leave the market for a better opportunity to buy. These investors have the tendency to get trapped in the market after buying some portfolio with the attempt to take profit and leave the market again due to their greed and impatience.
For example, you have the money to buy aggressively, but you may not be able to invest with it due to some problems. For example, you are not able to transact due to some problems or errors in the bank where you have deposited the money. You know that after some time or within 2 or 3 days, your bank account will be fixed or you will be able to transact again. But you have to be confirmed that you will get the money after some time. In that case, you can invest for some time with emergency funds.
I would never support buying aggressively because the wise and rich investors don't engage in that because I a lot of mistakes can be seen buying too much at a short period of time. It is good when we distance our investment strategy and buy at an interval. This is the same DCA strategy that Micro Strategy is using to accumulate thousands of Bitcoin without getting choked up at a certain price. There are so many profits to be made when buying at different intervals, giving a breathing space to buy at different prices.