So even if a person cannot afford to invest, I think it is necessary to form an emergency fund even if his basic needs expenses are reduced to a minimum.
What is the need of having an emergency fund when you are not ready for Bitcoin investment? It will be better you use it as your discretionary income and start accumulating Bitcoin gradually with it, emergency fund can be provided later instead of having it and you are not accumulating Bitcoin due to lack of discretionary income it will be important you use it in the place of your discretionary and start accumulating Bitcoin regularly using the DCA strategy.