Still wonder why they didn't include real estate but yeah they were right with their sayings but the truth is that if I have the options to go for them all, I wouldn't hesitate because all three assets are easy to trade not like land or real estate properties that would have alot of physical procedures and seller always seem lucky when he .eats a buyer.
Basically I will go for cryptocurrency(bitcoin) because it has more possibilities of appreciation than the other assets and it grows even more faster than gold or silver.
Bitcoin  will always be my first choice of asset investment.