...So, losing everything we have earned in one day will not happen to someone with enough knowledge. That will only happen to those who lack knowledge of trading skills; this is true. It's something that others don't understand well because their only thought is to make money, so the end result is always not good.
Even if a trader has sufficient knowledge for futures trading, but does not comply with risk management, then will eventually lose all your money. This is exactly what happened in the case described by the OP: a stop loss was not set, the transaction amount allotted for opening an order was exceeded.