I had a connection through Geneva and while my international mobile phone coverage covered the UK and Germany, but Switzerland wasn't included. The gate for the connecting flight was through an unsecured area, so I had to show a boarding pass again, except the United app which had the digital boarding pass couldn't connect (because of no internet access) and I almost missed my connecting flight.
Luckily I had printed out the boarding passes, but they were buried in my carry on. So I had to unload the whole thing to find it, but I did. If I had only a digital boarding pass I would have been out-of-luck.
When you buy a ticket and get a boarding pass, it typically comes in more than one form. When I fly, I get an email copy as well as the apps copy which I can then add to my Apple wallet. Accessing it at that point does not require an Internet connection.
I just described how I have two extra back ups, and yet, it has never happened to me any more than a decade I’ve been using these passes.
Worst case scenario? The gate agent prints me another one after they look me up in their computer. I know this, because I’ve seen people lose their paper boarding passes, and they had no back up at all. It took them five minutes to get another one.
I choose not to live in fear of a problem that doesn’t exist.
As I’ve repeatedly mentioned, I am prepared, with redundancies. And since I’ve never needed them, suddenly living in fear that I should just because you say so would be irrational.
What you’re describing is paranoia. Again, something I avoid.
Maybe I'm old school and I keep printed maps, tickets, all in a folder on my suitcase.
My phone has all that info too. But then it's a single point of failure. And I've absolutely had the paper ticket save my ass because my phone could freeze or restart at critical moments.
Like I mentioned elsewhere, I also have my Apple Watch and my iPad to use in case my phone has a problem. But in all the years they’ve been digital passes, that’s never happened.