My wife thinks I should sell!

Started buying in mid-October at $68K. I've been able to build up a little more than 1.5 coins. My wife wants me to sell cuz she can't wrap her head around not being able to hold a Bitcoin in her hand. She says, "How is it valuable?", "It's made up?", "what if it crashes or the internet goes down?" I told her not to worry about it, it's not for us it's for our future grandkids. ????