Every Bitcoin investors stance whether we're still in it's early phrase or not after approximately 15 years depends on individual perspective towards it, an investor who is believing that Bitcoin would reach $1,000,000 in the next 10 years would consider now as still early.
Bitcoin still having plenty of upside doesn't mean we're still in its early days. If expecting more upside is all it takes to call yourself an early adopter, then that logic works at any time.
Even if BTC hits $1m 20 years from now, would people buying at that price still be early adopters just because they believe it can go to $10M?

Those that are holding it as a store of value and a hedge against inflation would mostly not be bothered about whether we're still early or not, their main focus is that they are holding an asset that is decentralized with limited supply that has proven that it can sustained it's value in the future.
For an asset to count as a store of value or inflation hedge, it has to prove itself to the world first, and that takes time, a lot of it.
Having the same properties as other stores of value on paper doesn't make it one by default. Bitcoin took 17 years to prove that.
I would say that Bitcoin has done tremendously well if you're looking at it's market cap considering that it is a relatively new creation so either you think that we're still early or not doesn't change what Bitcoin is and it's potentials to reach ATH.
Bitcoin still has plenty of upside and could hit $1m. But again, having that much upside doesn't mean we're still early.