...do great speakers increase in value over time in the vintage market?

Hello to all...

I have a pair of JBL L25 "PRIMA" speakers, made 1972, case in 7/10 shape (not repainted), surrounds on woofers reformed several years ago, grill cloth replaced several years ago, includes JBL badges on speakers. Original 1972 price $169/ea. 

Recent searches of this speaker in the vintage market show prices 50% OR MORE than the origional issue price: ???

Is this that good a speaker design? - I have read comments saying it his/was one of the best speakers ever made by JBL (at that time?) - and I do luv their sound (which I now wonder if I've ever really heard them?) especially with well-recorded jazz and have the ability with little power to ROCK OUT!

(Would greatly appreciate any comments by those who have/had these over the years...)

DO GREAT SPEAKERS INCREASE IN VALUE OVER TIME, or do/should all depreciate in value...

u pay to play in this hobby

smarter folks pay a lot less
Yeah, let's just forget inflation in order to come to the simplistic conclusion that you really get ahead with a vintage piece of gear. Not to mention the ever present possibility of repairs, which BTW, would not be cheap. Let's not forget that since SOTA is a moving target, vintage gear always gets relatively worse sounding, if you actually use it, compared to newer gear. 

The Dunlavy's still have a following. After going to multiple audio shows, I'm still quite content with mine in multiple systems.
What douglas_schroeder said, which should be obvious. I think you would be hard pressed to find very many pieces of audio equipment that are worth more today than when new when inflation is taken into account. There will always be exceptions to the rule.
It's funny some do and some don't.