I think this is missing one other crucial factor in GOG becoming established: they targeted a niche.

Seems like a lot of people don’t really know this any more, but GOG’s ‘thing’ didn’t used to be a focus on being DRM-free, it was a focus on making old games accessible again.

GOG used to stand for Good Old Games.

Until GOG came along, publishers had next to no interest in making their older games available - things like Doom, Monkey Island, System Shock, Star Wars Dark Forces, etc.

Hard to believe now, but none of these games used to be available to buy anywhere - if you wanted to play them you had to either find a torrent or visit a dodgy abandonware site. It was GOG who identified that gap in the market and established themselves as the store for legally owning digital copies of these old games for the first time.