There is no such minimum or required amount to start mate. For most people, I think what they consider is how much money can you actually spend and use as capital that even in the risk of you losing it would not affect your assets or your life in general. If you can stomach such money to be lost, then for you, that would be your "right" amount. It would be nonsense to invest everything out, if at the end of the day, you won't have any money left to support your life or your family.