The majority of revenue comes from rich regions such as USA and Western Europe. Many regions, such as Russia and Eastern Europe, will buy software but only at a significantly reduced price. Look at average income by country and it makes total sense.
If you sell your game for $50 in the US and $5 in Russia then everyone will just change their region to Russia and buy your game for $5. Or Russian keys will be resold to Americans for $10.
You could sell your game for $50 in Russia but then no one would buy it so it's a waste of time. You could also sell your game for $5 in the US but then you won't make your dev costs back.
Yup.