Piracy

When it comes to individual copies of games, there's not really an "at profit" price. Either it sells enough copies to cover the development costs, or it doesn't. Like let's say an indie game cost $100k to develop, and after taxes and the storefront (i.e. Steam or the PlayStation store) the net revenue for the dev is 50% of the sell price.
Using Pizza Tower's regional pricing as an example, it's $20 in the US Steam Store and ~$0.80 in the Argentina Steam Store. So with those numbers (i.e. $10 revenue for US sales and $0.40 revenue for Argentina sales), you'd need to sell 10k copies to become break even if all sales were in the US compared to 250k copies in Argentina.
So if people all over the world are using the cheaper country's price, it becomes a lot harder for the game to become profitable, and if that abuse of the system is widespread enough, the devs will either need to raise the price so that it's no longer affordable for people in countries with lower incomes, or remove it entirely from that region. Most devs would rather people have a reasonable, legal way for people to play their games, and key resellers can make that harder

Profit for game industry is relative to sales, because the cost per digital game is practically $0, it's all paid upfront.

You can sell a game for 1 cent and if all people on the planet buy it, it will probably still turn a profit.