Are you a child between the ages of 3 and 5? Because that's the typical age of a participant in the marshmallow test. This is like scoffing a kid not finding something on Dora the Explorer.
Within the parameters of your analogy, my point is closer to scoffing at the experimenters for making sweeping conclusions based on kids being able to find a single item on Dora the Explorer. Sure, maybe the kids who failed to find it had a learning disability, or maybe they weren’t that stimulated by being forced to watch a show they disliked when they could just go play something else. Even with the conclusions having been drawn years later, where the finders performed better academically, that could still indicate the non-finders were simply uninterested in the way most schools work by forcing you to be there and listen to certain subjects at certain times. Perhaps they would’ve thrived in a freer environment where they had greater freedom to pick the subjects for each day.