A smart trick to the boy, simply buy Bitcoin with that money and wait for the future to show you the real growth.
I don't think that you can be so rich to reject that kind of money, especially in Nigeria. Maybe millionaires in USD terms, not in Nigerian currency, could actually reject it and live good, but even if you're far above the average income in the country, that should be huge money for you. A life changing sum of money.
How much he'd be able to improve his life, or the life of his whole family? Probably by a lot.
If you don't want the money for yourself, do something good for others. Help your neighbors, put it in a school fund for your child, or in a savings account so that your kid doesn't have to beg anyone for money when he makes bad choices in life. Don't throw it away or give it back to the casino.
If I were the kid and my father said that the money won't enter his house, I'd agree with him and put it in the bank