Yes... there is a very interesting generational thing going on here.

Bluetooth headsets were very popular among a certain market segment (business people who made a lot of phone calls), but saw very little adoption outside of that. At that time, you often had to buy an expensive business grade phone to get bluetooth functionality.

Then once Bluetooth was common in cheaper phones, we see a completely different market segment (students at schools) rapidly adopting bluetooth for a completely different usecase (file sharing). It's hard to find two market segments that are more isolated from each other.

I don't think file sharing could have ever driven bluetooth to mass adoption on its own, partly because companies always overlook what school students are doing with technology. But mostly because the file sharing usecase required mass deployment of the technology before it could take off.

When I was in high school, I had a palm PDA with IrDA that could do file sharing. But did I ever use it for file sharing? No, because nobody else had devices with IrDA. IrDA never hit the market saturation it needed to be actually useful, so there never was much demand for it (despite the hardware being really cheap, especially compared to a dedicated bluetooth radio)

Bluetooth headsets worked as a killer app in those early days, because a single BMW driver could buy both a high-end phone with bluetooth and a headset from the cellphone store and get the complete experience. It worked without market saturation.