I own a $25,000 Lange & Söhne. While watches are a time-honored way of signaling, I didn't buy it to show off. I've actually never met anyone who recognized it, and off the top of my head I can't remember ever even getting a compliment on it. I'd never buy a Rolex, because they're too loud :)
Here's the disconnect you're struggling with: you don't value watches. Or more accurately, you don't appreciate them beyond simple utilitarian timekeeping. That's fine, most people don't really care about them. Instead of trying to relate to people who buy expensive watches by valuing watches - which you clearly don't - relate to them through the broader experience of spending a lot of money on a hobby.
Do you have any hobbies you spend "a lot" of money on, perhaps more than what's required just to engage with the hobby? Keep in mind that "a lot" is arbitrary. I have a friend who spends thousands of dollars on card games. I don't see the appeal, but it makes him happy and trading card games can be a fun activity. That hobby "doesn't require" a purchase of the most expensive, collectible versions of various cards, but people do it anyway. I'm pretty sure my friend doesn't do it to signal that he can spend that money :)
The point is this: what's expensive for one person is affordable for another, and what's valuable for one person is frivolous for another. There's not much beyond that. It's all relative - in principle it all comes down to whether or not you spend strictly more than you need to on a thing so you can enjoy it beyond its raw functionality. If you do, then you're no longer treating that thing as a tool, you're treating it as a form of art. Like all forms of art, expensive watches are polarizing and subjective, and they attract a subculture of people who discriminate between things which seem utterly arbitrary to people who don't appreciate them.