Err, no. There is clearly a pattern to the data, and drawing the conclusion that self-assessment and actual skill are uncorrelated is not what you should do (the simplified pattern being that unskilled individuals overestimate their skill, while skilled individuals underestimate theirs, or a regression to the average if you will).
At any rate, even if we don't take that into account self-assessment is worth plenty as demonstrated by many studies which manage to get coherent data from self-assessments. Sure, you should take them with a grain of salt, and you can expect biases, but no need to throw them out.
