You can disagree, that's fine.
But anything you can touch has the risk of being forged or destroyed.
The whole point of bank notes was that they're centrally backed- someone would take the responsibility of ensuring that it's hard to forge and backed by something "real".
But centralising it so completely has pretty concrete drawbacks, which is fine, if your infrastructure is perfectly reliable and your banks are trustworthy.
History has shown us that infrastructure is never perfect, and banks are not perfectly trustworthy. So, hedge your own risks.
A personal tragedy (losing some money) is materially different than the entire economy being screwed because of a programming issue, or a city being screwed because of an internet outage, or a person and their family being (additionally) screwed because they offended a politician.
It's just.. different levels, and the centralised convenience becomes a pretty catastrophic impact in the worst case; and on a long enough timeline, the worst case is inevitable.