Sure it sounds crazy, but thinking about how I live financially now...I touch cash maybe three times a year these days. My local farms use Square Stands to pay for pick-your-own apples & blueberries. The vending machines at work are all swipe. Drive-through restaurants take cards. I think the only times I really used cash in 2015 was when the credit card machines went down at the store (fortunately I carry a few bucks for backup) or if I went to a festival with vendors who were cash-only (although a lot of them are using stuff like Square magstripe readers on their phones to do payments using cellular data).
Still, it seems crazy to go 100% digital in a world with rampant identify theft & hacking....if they can hack Target, Home Depot, etc., they can hack your digital cards & other stuff, so I'd be worried about getting my identity totally nuked. I had a buddy whose identity got stolen and he is still dealing with the fallout many years later from all the stuff that was purchased under his name.