But the claim above was that having low confidence was correlated to higher skill. Ie, skill and confidence are anti correlated. The chart does not show that. The lowest data point for confidence is the point on the left of the chart. This is also the data point corresponding to people who have the least competence. Having low confidence is not evidence that you’re secretly an expert. Confidence and competence are still positively correlated according to that chart.

The Dunning-Kruger effect is not so strong that there are scores of novices convinced they are experts in a field. But in your case, I admit the data may not tell the full story.