The mistake that you, and quite a few other people, are making is that what makes money security has something to do with transactions. It doesn't.

Monetary security is about maintaining the quantity.

When you own some bitcoins, you know precisely what fraction of the bitcoin ledger belongs to you, and that's why Bitcoin is value. What you do or do not spend it on is immaterial.

The best money is the one that provides the most quantity security and is used by the most people.

There is no reason whatsoever to prefer any money except the best money, which is why the market will eventually converge to a single money.