From what I understand, there are several metrics to measure bitcoin adoption at any given time.
-Number of Blockchain Addresses
-Number of Transactions per Day
-Average Daily Transaction Value
-Number of UTXO's
-Use Cases (Bitrefill, Binance (top exchange), Trezor (hardware wallet), have directly correlated to the price increase of BTC hands down.)
-Total hash rate (it was at an ATH the other day, despite miner revenue's plummeting and electricity bills soaring)
-How much do the top 1% of wallets hold? the next 49%? the rest of the 50%?
Obviously some metrics such as number of addresses, top holders vs. least funded addresses, and a number of transactions are kind of ambiguous if you are trying to calculate real human actions. From the way the space is, many individuals manage multiple wallets that are created and destroyed on the fly, money sent to and from them for the sake of obfuscation, and even exchanges trading crypto within artificial accounts between each other to display false volume.
The way the world is going now, people are going to dump their fiat for crypto. That's the way I see it.
The number of bitcoin wallets vs the balance on the network and also miners' hash rates are all determinant factors to point out the level of bitcoin usage and that being said exchange and other services are just one segment of the entire network, when the numeric is accumulated in total then the can conclude the level of adoption.
And considering the level of Bitcoin adoption in terms of usage and also the network engagement we may see a rapid multiplication in volume in the Bitcoin network.