Its for the people that only buy when its a "good deal". Its usually for old games that are well liked or for newer games that are maybe a year old now. The non sale price is for people who can't wait for the discount. Sorta like waiting for a movie to go to video/streaming rather than go to the theater.
I’m not rich but I’m definitely not poor. I only buy video games when they’re like $30 CAD or less. Only time I went against this rule was for Baldurs Gate.
Can you elaborate where your confusion lies? It's a digital good, there is no marginal cost. So they can pretty much price a game however they want. So pricing is mostly about maximising revenue, i.e. get as many sales as you can at the highest possible price.
A sale is a relatively straightforward strategy where you first sell the game at a high price to all the people who are fine with paying a lot, then you lower the price to sell more copies to the people who weren't willing to pay the higher price. The result is more total profit. There is a time limit too to create a sense of urgency ("I better buy now so I don't miss the opportunity").