my father in law recently told me that I'm not a member of the working class. I don't remember his exact argument, but it boiled down to I don't work in a factory or on a construction site, so I'm not a working person.
And that's nonsense. The work you do has nothing to do with your social class. The question is whether you make your living by working (selling your labor) or by owning things (real estate, money, stocks, etc.)
I doesn't matter whether you're a mechanic, a miner, an office worker, a journalist, a sex worker, a twitch streamer, whatever – if you are forced to sell your labor to make a living, then you're a member of the working class.