Years ago I found my father's wallet and only saw about ten bucks worth of currency in there, and thought that was all the money our family had in the world--I was very worried about how we were going to live on that ten dollars! (Don't think it's cute--I was nineteen years old at the time). Of course in subsequent years I learned that most people keep only a fraction of their net worth in cash.
How much cash we carry on ourselves varies from person to person, depending on the following:
1) Cocaine addicts only need a few crisp twenties in their wallets, since everyone knows that genuine Medellin Marching Powder always snorts best with a twenty.
2) Mobsters have to carry a fat bankroll since they do most of their transactions in unmarked currency. A roll of hundreds will do just fine. No wallet necessary.
3) High paid executives (with millions on their balance sheets) generally carry less than a buck in currency, preferring to do everything on the company card. To them, cash is for poor people! Unless of course they want to buy a hotdog in which case their assistant needs to come along to do the transaction.
4) Germaphobes also don't work with cash, since it carries the germs of all previous users of the cash. Instead they prefer to shout their credit card numbers and expiration dates to the cashiers from a safe distance.
5) Anyone carrying a large stack of ones is probably a stripper who hasnt' been to the bank yet. But if television has taught me nothing else, that stripper has a heart of gold and is trying to raise her son in this tough world. Don't judge her!
6) Anyone carrying foreign currency is either (a) a jetsetting businessperson or (b) a hipster douchebag who's trying to show off that "he just can't find a bank that will exchange his 'bahts' without charging an outrageous fee". If they're wearing a fancy suit, it's (a). If they just gave you a compliment but did it with "air quotes" then it's (b).