I think you're missing 4). the obsessed, which can be broken down into 4).A: are building keyboards from kits and programming custom layouts 4).B: are spending

I think you're missing 4). the obsessed, which can be broken down into 4).A: are building keyboards from kits and programming custom layouts 4).B: are spending hundreds on ebay for prior-era keyboards, or, on modern rebuilds of them