EDIT: Looking into this a bit, I don't think they're fake... it seems like most of the websites are "powered by X" where X is some CRM/website builder solution targeted at car dealerships, like these [0] [1]. They all have marketing/advertising features, and there is likely some sharing of contact data on the backend, or contact lists are outright sold as "leads"
The frequent flyer group have just taken it from my membership details.
I don't bet, but I've worked as a statistician, so there's probably some connection there with past probability and modelling work or getting odds from these sites.
The real estate group I'm guessing is from contact details given while looking for houses that they've used without my explicit permission.
Audi is interesting because I've never had a car in my name, and haven't had one in my household for several years. Haven't so much as stepped in a car dealership. I'm guessing they must have bought(stole?) it from a rental or car-share company database...or a marketing list somewhere, but its certainly not from anything I've done first hand.