I can’t imagine the circumstances you would need to live in not to find a mobile useful - maybe in a care home, if you have access to a phone but are unable to make calls for yourself. Otherwise, it’s invaluable, it removes so much hassle from your life. I use mine for sat nav., as a route planner, to be able to talk to people and drive at the same time, to make contactless payments, to check facts on the move, to take photos of plants I like and identify them, to scan the code when I go to museums etc. and get the guided tour narrative and to check my local shops have something before I make a trip, as well as the usual phone calls and internet use. - and probably more that didn’t immediately come to mind too. My parents are both in their nineties and they have them too, it provides them with reassurance when they are apart doing different things. Mobiles are one of the most useful things to have come out of the last 50 years I think.