This is the vacuum argument. Bitcoin will never ever exist in a value vacuum. Nothing will ever exist in a value vacuum. There will always be other spending options, and versus Bitcoin the other options will come out on top for most people.
In fact things are going in the wrong direction for Bitcoin. It's actually becoming less of the global share of spent (as in MoE) currency as the days go by, not more. In other the tiny embers of MoE are dying.
Bitcoin is all about store of value.