What exactly do you not understand?
If there is a "sale", people get into "there is a sale" mentality. The worst kind is theblack friday things where customers brawl each other.
You can't have a sale each day, or it would not be a sale.
So yeah, it is just you. And all the other small developers that are struggling. You are unknown. People did not put your games on collection to wait for a sale. At least not in any big quantity that you would notice.
Additionally, people have this personalized page
https://itch.io/library/recommendations/on-sale
And you might have noticed that not all items on sale will appear here
Also, you seem to sell assets and not games. Your customers are not sale crazed players, but developers.
This has 7k items https://itch.io/game-assets/on-sale
Games only has 2k, which is rather curious, since there are many more games than assets https://itch.io/games/on-sale
You are the only one here https://itch.io/game-assets/on-sale/tag-wastelands, but for a sale to work, you need to have traffic to begin with.