Is this....a serious question? All new iPhones are 5G compatible for the start and they sell millions, and loads of other manufacturers have released 5G compatible phones. In fact I'd risk a guess that if you bought a phone in the last 12 months it's likely to be a 5G compatible phone.

I bought a Pixel4 in March 2020 :(

Assuming you meant Pixel 4a, that one does not have 5G. The "4a 5G" model does, though, but it came out later in the year.

No, the regular Pixel4. No 5g.

Probably anyone that has signed a contract that came with a free phone in the last year and a half, anyone upgrading iPhones.

Lower cost prepaid carriers are also pushing 5G phones heavily (albeit somewhat crappy ones), and offering them for free.

It doesn’t matter if you have a 5G device, it is a function of the increased tower density. Those towers are capable of the old frequencies, too.

Alot of people buy new Iphones.

You don't even need iPhones - most of the cheap prepaid brands that you'd see next to a payday loan shop are offering Samsung's lower grade phones or OnePlus 5G phones for free if you set up autopay (it's locked to that carrier). Of course it comes with even more privacy-violating bloatware than ever, but still - 5G is no longer a rarity or expensive.

I’m guessing people who flew into DC on a weekday are more likely than average to own a decent smartphone. QAnon folk don’t seem to avoid mainstream technology in the quantity HN users do.