and do not mind those who says that trading is hobby, is just like saying they love losing money because we can also refer trading as gambling and you know what gambling is. You can easily lose what you use in gambling or trading, therefore whatever amount you are using for trading should be equivalent to what you can afford to lose.
I agree that a trader should use the amount of money that he can afford to lose but I do not agree that we can refer trading as gambling. Trading and gamble are completely different but their risks are similar because most traders do not know how to trade but have greed and doing trading like gambling.