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.
"No reason whatsoever" is the kind of snotty absolutism we expect from a Fundamentalist Monopolist.
You may have no reason whatsoever for using altcoins, but others certainly do. That's why our alt sub was promoted and expanded.
"Best money" depends on the context. Traditionally you preserve value with gold and transact with silver, making small change in copper.
Bitcoin can have the lion's share at the top of the Pareto distribution, but we should expect a long tail of other crypto with varying degrees of suitability for substitution. If people prefer to use coins based on a silly picture of a dog or constellations of prime numbers, they will. You need to accept that and move on.
The problem with maintaining BTC's monetary security and the GigaBloat fork is that huge blocks will have predictable and unpredictable negative effects on the network.
Many do not with to risk BTC's secure store of value function to chase the impossible dream of every Coke machine, laundromat, and hot dog stand transacting directly on the One True Blockchain.
We were sold Bitcoins backed by a defensible network accessible via TOR or other slow/hardened connections. Changing the quality of that social contract is no better changing the quantity 21e6 (The Sacred Number).