After hurricane Maria hit Puerto Rico, the blackout lasted for months. I assume no one was getting any money out of ATMs or using credit/debit cards or Apple pay or anything like that. You don't have to distrust the financial system to want cash on hand. You just need to have a rudimentary understanding of the fragility of the current system. I simply cannot see a cash less society ever existing while the only alternative is powered by electricity. Electricity can fail way to easily.