I don’t think vintage basses really have a much better sound. I love my vintage bass (less for the sound and more for what it means to me).
I’m not a vintage bass hater. But I do think £18.5k for the 63 Jazz Bass is crazy. It’s not a Jaco-style 62’ slab board or a stack knob. It doesn’t even have the mutes.
Stick it through an amp and it’ll sound the same. I speak from experience (they really do!)
Or, to put it another way, if nobody ever knew you owned it or know how much it was worth, would this bass be worth £18.5k to the person?
Vintage instruments at this level are speculative investments or status symbols. That’s all good.