I agree that a person should not be dipping into his emergency funds for BTC buys, but there could be situations in which it makes sense if there is variability in income and expenses, and there is also a decent sized emergency fund. There also may be decisions to buy a certain quantity of BTC no matter what, so if the cashflow over several months is fluctuating, the income might not meet expenses, and yet there still might be expectations that the following months or the month after, the emergency fund will be able to be diminished with the short-fall, and part of the reason to have an extra large sized emergency fund is to be able to buy BTC every month/week. . or whatever might be the priority that is pre-established.
Anybody that uses funds for emergencies to invest in Bitcoin is not a wise investor because problems can come at anytime when he/she will need some money that he will use to settle down some things that needs to be settled..
Having an emergency funds might make an investor to hold more longer than he or she planned to hold. Reasons are because when you are saving and still accumulating Bitcoin and on the other hand you have funds for emergencies, then what will the person want to sell his coins for? Nothing,,, unless they will want to use some of the profits to complete a project and other things that can be bring more money to them during the week or month.
There are some people who works in a company that don't pay workers salaries on time (delays payments) and those people if they are invest in Bitcoin and they are not saving some funds for emergencies and just saving for nothing, by the time month end and there is no payment they will want to sell some coins and use the money to support them self untill payment is made.