The question is how you view your instruments: as a working piece of machinery or an appreciating asset. It can be both, but the former will (in time) affect the latter, with wear and tear and inevitable changes needed affecting the value of your instrument. I have the jack socket of my 66' re-soldered for example, which now renders it slightly modified, but I couldn't be doing a gig with a crackly bass or my bandmates would have killed me!
It's also worth considering how liquid that asset is. The market for vintage guitars is buoyant at the moment, but it crashed after the last recession and with consumer debt currently at huge levels, it could happen again. Then your prized bass may be worth a lot less than it currently is. Markets being dynamic and all that. If you've bought the best player (that suits you) then you should be in a good position.
As someone who spent their 20s and early 30s recklessly wasting money this realisation is slightly jarring, as I now recognise that I sound a lot like my dad.