The marshmallow experiment is too simplistic, but for millions of years we usually were better off eating both marshmallows. Now we have supermarkets with products full of sugar. You can consume an unhealthy amount of sugar eating a few fitness granola bars, half a liter of fruit juice, or a single bar of chocolate.

We are especially vulnerable to superstimulus (exaggerated signals), which is what makes McDonalds, TikTok or surgically augmented breasts so popular. More sugar, more salt, more silly faces, more breasts. Even if we don't prefer them our brain is drawn to them. They used to be important signals. Youtube video thumbnails almost always feature people making faces, TikTok is short videos of people making faces. It's a race at providing better superstimulus. A lot of our culture these days is a constant bombardment of stimulus and we are not especially adapted to it.