If you're talking about Christianity than I disagree. Sins are not limited to the Ten Commandments and extend to many other areas.
Christians are called to be good stewards of their resources, using their money and time wisely. The example you brought clearly put desire for money over wellbeing of your family. Definitely a sin.
Well, I didn’t border my statement on a particular religion, but then again, let’s assume we are talking about Christianity, you’re not completely wrong, but then again, what if the intentions behind the actions weren’t exactly how you’re thinking it. Lets assume the person in question is in custody of his family’s money which they intended to use for something in the future, and since they didn’t have any use for it at the moment, decided to wager it in order to make more profit until whenever the money was needed and then things didn’t go as planned.
Even in the bible, if you remember vividly, the parable of the talents, where a master entrusted some money/talent to his servants and went on a journey, the servants also used the money to trade, either in business or whatever, I don’t know, but they made some extra bucks for their master and he was pleased with the servants, what if this was the same very intention the person has and spiral out of control, would you say he has sinned?