I say many are! I have met a few who seem to be grounded but the money and power has a way of invading their sanity and they can be unstable when that happens.
Think about it...
You buy what you want.
People **** up to you and blow your ego up.
You get treated differently most of the time anyway.
You start counting your money to often.
Ypu believe the hype and worse your own hype.
At some point you have nothing but addictions and desires. Power, women, respect and anything else that you feel money can buy.