It is good for anyone thinking about buying Bitcoin and he/she should be smart while doing it. We should never use money that we need for regular things like rent or food or bills. First we need to plan our money and decide how much we can afford.
It is a simple question like how much money you are able to spend for investment. Another important question is how many percent that investment capital is in your whole capital. To have good financial management, your investment capital should never be 100% of money you have. If you do this, you nearly can not afford to lose all in your investment.
This bad start will make your mentality very weak and you are possibly more vulnerable to market volatiliy, fud and bear market can shake you out of this market when you are extremely panic, or you might be liquidated by exchanges.
Sometimes there may be weeks or months when we do not spend as much money on our household needs. When that happens it is good to put little extra money into Bitcoin. This is sensible way to buy more Bitcoin without risking our financial security. It is much better to do this than to use money that we need for our family. With this way of thinking about Bitcoin is good and focuses on building our investment slowly other than making quick decisions based on what everyone else is doing.
If you plan your investment is gradually accumulation with time through your spare money, it sounds good. After spending bills, assumed monthly bills, you can split your remaining money in two parts: one part for emergency fund, and another part for invesment. This approach will help you to increase your emergency fund as well as your investment capital with time.
A split ratio between emergency fund and investment fund can be 10/90 or 20/80, that means you use more spare money for investment fund (80% or 90% of it) than for your emergency fund. The bottom line is you keep building up emergency fund with time.