It's like Netflix- scrolling around looking at previews gives you all the dopamine, by the time you select a movie your brain just craves the phone and it's just background. You don't get doordash because you want to order a good, balanced, healthy meal. You do it because you want to scroll and find something that makes your brain tingle. By the time the food shows up cold 45min later, you're already on to the next thing.