If money could guarantee someone peace of mind, then the man in person would've spent half of what he's acquired to find peace but what we was going through was beyond his wealth, and he's a prove that one can have all the billions and still not get peace or happiness. I might be wrong though but what's your opinion?
Money does not guarantee happiness and neither does poverty. Less we forget, wealth and happiness are two different things. Though they are likely to be influenced by each other but yet, they are independent.
Wealth is about having money to solve your financial problems while happiness is the state of your mind. You can have a stable mind rest even without wealth but having wealth is likely to give you more rest of mind since you have less problem to bother about. The reason for unrest of mind is due to series of problems and truth be told majority of these problems need finance to be solved.