As a retired financial advisor my opinion is there might be better places to invest your money for capital gain. A couple of reasons.
One, supply and demand. There are a lot more basses being made to today by more manufactures than 50 years ago. Not to mention the number of manufactures and boutique builder making basses of a higher quality than Fender weren't around 50 years ago. Let's just say there isn't likely going to be a "sellers market" like there is today.
Secondly, with the advent of AI may make musical instruments obsolete, not to mention making musicians largely obsolete. I honestly believe that musical instrument are going the way of the rotary telephone, with instrumentalist musicians left swimming in the tar pits of the human experience.