If I heard McCain's comment correctly, he said:
"I think ... I'll have my staff get to you,"

I didn't hear McCain say he didn't know. Instead of giving an inaccurate response, he said his staff would get back with him to give an accurate response. Besides, many wealthy people don't know exactly what property they own when others are paid to purchase & manage investment property.

So why is Obama jealous that McCain and his wife have made good investments thoughout their lives?

I'm surrounded by people who buy many investment properties to rent through HUD for people who cannot afford to put a roof over their head otherwise. These are mainly single mothers or senior citizens who rent the homes that are investment property. So owning many homes for profit is quite common.

I don't know what McCain does with his personal investment property nor do I much care as long as the property was purchased legally and is used legally.

How much property do the Clintons, Kennedys, Obamas, Bidens, etc have? Who really cares?
One other little detail, isn't part of the American Dream to be able to become wealthy instead of getting the same money as your neighbor no matter how much you strive to get ahead? Isn't this part of what makes the USA one of the greatest nations on earth?

We're Not Socialists whose government takes away our earnings to share with those who have made poor investments or not worked as hard - at least not yet.