Yes, I completely agree with you, but you forgot to mention one thing, that is an emergency fund to protect your investment. It is not enough to invest, but an emergency fund is very necessary to protect your investment. During investment, we face many types of financial crises such as medical expenses, job loss, weekly or monthly extra expenses, etc. It is mandatory to have an emergency fund so that our holdings do not get stressed during all these unexpected financial crises.
I think you are mistaken with the placement of emergency funds for investment because in financial conditions emergency funds are actually not very suitable to be used as investment funds but the function of this emergency fund is more suitable to anticipate needs that may be unexpected such as when you need funds for any repairs (such as houses, cars or others) so making emergency funds as a focus for investment is clearly a mistake even though it may return to yourself.
Investment funds and emergency funds must be separate for whatever reason so that when you have discretionary funds from monthly income, as much as possible we divide it into several things including for investments and emergency funds (although emergency funds are flexible especially when we have saved emergency funds for several months before).
I agree that emergency funds should not be used for investments. However, you are wrong in that @Tongly did not actually recommend buying Bitcoin with emergency funds in his statement. His main point was that it is necessary to keep separate money so that you do not have to sell Bitcoin in case of unexpected expenses. In this system, emergency funds protect investments, although the money is not in the investment.
Again, once a few months of expenses accumulate, the emergency fund is no longer suitable for other purposes. The amount of money that is set aside for emergency needs is its job to handle that need. If your money is more than the necessary protection, then you can consider it as a separate reserve money. Then the decision on its use will also be different.