Well, he believed his own hype, apparently, and wasn't afraid to let others know of his imagined brilliance.
I guess there may be something in that. The phrase "Rules are for the obedience of fools and the guidance of wise men" is oft attributed to him.
Yet if he'd obeyed the rules banning aerobatic fannying about he'd have not lost his legs.
If he'd obeyed the rules about keeping formation and not going zipping off for a dust up at the first sight of a tempting target he'd have probably not been shot down and ended up as a P.O.W. Indeed, no Luftwaffe pilot ever claimed the "kill" and examination of records post war failed to identify a candidate, so it is speculated that his inability to stick to the plan may well have ended up with him becoming a victim of friendly fire, the 'loss'of ampilot and a valuable aircraft.
And despite his history of rule breaking and consequential Class 1 Clusterfoxtrots he never missed an opportunity to tell anyone who'd listen how brilliant he was. I believe the Americans call that sort of fellow a "jerkass."
Sadly the general view of him is the warm and fuzzy Kenneth More person, which was a long way from the reality.
Many folk reckon he was a bigger nodder than Stirling Toss, and that takes some doing.