My parents use an Ubuntu PC for all their online banking on their saving accounts. My father knows how to keep it up to date and I help him to upgrade it to the latest LTS every 2-3 years.
It's just a peace of mind, otherwise I will be paranoid about their online security. They still do usual stuff on their smart phone and their windows laptop.
They can really use Ubuntu for all their needs at this point. I'm just too lazy to go there and install it on their laptop.