I think you may be confused:

"You are correct that adoption is not a guarantee of higher BTC prices".

Then...

"..rising adoption is a good bet."

"..betting on BTC is... it is a bet"...

Conventional "betting" is based on either fixed understandable statistics and/or pure belief.

And, in the case of statistics, the fewer reliable vectors on one end or the very large number of them reduce practically to guessing. I.e., Belief.