Functionality. As price range goes up, the amount of “difference” between the new price range and the last gets less and less. The exception would be customs, as they would be tailor-making every part of the bass including how it looks to your preference. Dropping huge money on that I could see, but the difference between a $1-2k bass and a $500-1k Bass is WAY less of a difference than a 500-1k bass and a $400-less bass.
I noticed this at guitar stores. Played a $5k Martin and then played a $600 Gibson (acoustic guitars). Did the Martin feel and sound better? Yes. Did it sound $4,400 better? Not even close. The difference was subtle, and honestly I’d record or perform with either feeling confident they would sound great.
It is pretty similar with basses. After the things that really affect the sound are all top quality…it’s harder to tell what you are paying for.