I don't know how left over funds after one has made all his expenses for the time being which is discretionary income and fund thats been kept for emergency or any unexpected stuff which is reserved funds will be the same,
You are getting it complicated you still tag emergency fund and reserve fund as thesame thing i think they are two different things, emergency fund has it purpose when it comes to Bitcoin investment reserve fund also serve on a different purpose. Emergency fund is there to care of real emergencies when they happened to prevent you from selling soon when the unexpected occur, while the reserve fund is there to accumulate Bitcoin expecially when there is a decline in price one can use his reserve fund to accumulate more Bitcoin so stop seeing emergency fund and reserve fund to the same.