I get that marketing can't be done like that, so it makes sense but that is why some people go against the idea of showing only the big wins.
I don't know if showing a big win is a proper form of marketing or not but all casinos do that (if they have sosial media)and I think why they do that because one image is enough to tell everyone what's going on, differently if it has to also display losses requires more image views unless the casino has a summary feature so players can know the end result all of gambling activities they do, are in a profit position or vice versa.