I couldn't put the full title in the subject line due to character restrictions, but here is the full question:
If bitcoin was fully adopted into everyday life, why would it ever be used for day-to-day transactions if the general consensus was that the price would always appreciate?
The market isn't always up, and when it's consistent on a specific value, using it as an asset for the transaction won't affect you much if and only if you've bought back at the same price. The OP makes sense, I understand the point, and I'm wondering why I'm still using my BTC for other things if it'll just go up. Taking profit, on the other hand, should explain why others continue to sell and use bitcoin for transactions, we have different approach on crypto, can't blame them if they're happy and satisfied on what they're doing.
People do have this kind of mindset specially when you are just new into this market where you do expect that price do continue to rise up without minding about the reality of this market which is really wild when it comes to volatility.
We do have different taking or views towards bitcoin and some of them would really be saving up bitcoin rather than on using it up or making active conversions.
Its a wrong mindset on believing that it would always go up but if you don't really mind much about on short term then holding isn't always a bad idea.