What is your reliable measure of Bitcoin adoption?

It's not reliable, but I go by how much I'm using it, how much it's relevant to my day-to-day life (excluding my chosen profession), and how much my frens (bitcoiners included) are using self-sovereign bitcoin setups day-to-day. And it'd be reasonable to round either of those to near zero.

I don't think that will change until we have something with lightning-like payment properties that doesn't require federation-like trust.