You're probably best deleting it. I don't know if Namecheap has a grace period or when you reg it - but if so you will get refunded or an account credit.
It only becomes an issue if you use it in bad faith, and you have no legitimate use for the name. If you plastered advertising on it referring to anything associated with the billionaire you mentioned, or emailed them trying to sell it to them, or used it to damage their reputation...etc, then you could have severe issues.
You're probably best off getting rid of it and avoid the possible risk, but that's just an opinion.