https://isthereanydeal.com/ regularly shows me titles on my wishlist that are cheaper on somewhere other than on Steam.
Steam sells up to 4 times cheaper to people who live in certain poorer regions, and this also gets the usual discount. So some old game sold for $10, might get a 75% winter sales discount, plus a further 75% off in poor countries, down to about 60 cents.
It's clever because it takes purchasing power into account. So a game that's about 1 hour salary in the US would cost about 1 hour on a Indonesian salary as well.
This is going to be really hard for many competitors to match.
Even the discount sites and Humble Bundle aren't able to match up against Steam in third world countries.