I think there's two variables at play here, one is anyone's personal ebb and flow with any particular hobby, and the second is the wider state of that hobby.
Relative to burn out, which I resonate with, I actually think it's #2 more than #1, at least for myself.
Some of the main factors driving this IMO are, relative to vintage, as others have already stated here on the forum, vintage passion is driven by discovery. The well has mostly dried up, and there's just not a lot of discovery these days. The UG subforum is a good example, it used to be very busy, and it's pretty dead these days. Not because of any decrease in people's passion for UG, if anything I think it's grown, but because there's just hardly any more discovery these days. Almost everything is tied up in collections, what little comes to market is often mediocre or extremely expensive or both. It's not super exciting to discuss what little UG inventory might be on the market from dealers at any given time.
The second issue is the commodification and investment banking mentality that has come into watches in recent years, with the likes of Hodinkee and everyone else. Without getting into an argument about if that's good or bad or whatever, I think everyone can agree it's changed things.
My collection has been almost completely static for the past 3 years or so, I just can't find much to buy or to talk about in the areas that I've focused (which has been mostly UG).
I still love the small collection that I have, but I pretty much just wear my Hulk 24/7 because it's very practical, except for the occasional dress up.
I hope things get more interesting again at some point.