Is this real or just a story?
Charles was foolish. How would he trust friend up to that extent? That is foolishness. We should not handle life with foolishness, bet separately.
Kelvin is now rich. If Charles is not rich, Kelvin may win anything brought up by Charles, except if Charles is rich and able to file a law suit with Kelvin. But even where is the evidence that they added money together to bet.
Agreed, there is a reason why it is never recommended to mix business and friendship, you may trust your friend but that does not mean that your friend is actually worth of your trust, so we must never mix the two, even loaning money to a friend is a risky proposition and whenever I have done it I have expressed to them that I do not expect to get my money back, but that I will not ever lend them any money again if I have not being repaid the previous loan.
In terms of business vigilance is the main thing we can't mix just because we are close to someone because business is business.
We must be able to block this so that everything goes according to plan. Even if it is your own family, sometimes in this business you usually can't trust 100 percent because when you are given the freedom, everyone will become greedy.