I was thinking about this scenario where a person steals some money and uses that to start a business and even becomes very successful and makes many times the initial money. I was wondering that if he gets caught, what would happen to the value he has created? I think that it is not fair to give all the created value back to the person the money is stolen from. I also think that the thief (here) has put some effort to make that business successful so he would not get anything back for his effort if all the value is taken away. What does the law say in this type of situation? (US-law)
In general, the law seeks to make all parties whole.
There is no mechanism for profit-sharing between thieves and their victims.
Victims of theft are entitled to receive their money back plus the applicable rate of interest (called the judgment rate). They are not entitled to profits or windfalls above and beyond the statutory judgment rate of interest.
What if the act of stealing the money has destroyed the owner's business and has left him with a lot of debt and bankrupt?
Criminal statutes provide for the return of stolen funds plus interest. Recovery of damages, as you describe, is provided by civil statutes and common law. So, to recover damages, the victim would need to sue the thief in civil court.