Suffice to say that sentiment is against Dan Sickles and I would not disagree with the majority. How ironic then is the undisputable fact that his move to the Peach Orchard salient and Emmitsburg road disrupted the Confederate plan of attack on the right from the outset, diverting a portion of the brigades of Laws and Robertson and having Anderson and Benning exert themselves in attacking the Federals posted between the Devil's Den and Wheatfield, besides seriously damaging (by Union artillery) the brigades of Kershaw and Semmes. Sickles may have been like that blind squirrel who still finds an acorn occasionally. His adversary Longstreet thought the Union won the battle because of Sickles' move (
https://civilwartalk.com/threads/longstreet-to-sickles-on-gettysburg-1902.145172/). The Confederates took the initiative at Gettysburg from start to finish, so it is ironic (that word again) that Sickles was the only one to disrupt Lee's plans by assuming the initiative himself, even if he was insubordinate and his motives questionable in doing so.
In fact, the Oxford definition of "irony" seems to perfectly define Sickles' actions on that day: "Ill-timed arrival of an event or circumstance that is in itself desirable." There are plenty of relevant sayings from history on this topic, but I will just quote one from Theodore Roosevelt: "In any moment of decision, the best thing you can do is the right thing. The worst thing you can do is nothing." Admiral Horatio Nelson, for one, disobeyed orders and won the battle of Copenhagen. But if one is going to be insubordinate, it is a requirement to win. It's the difference between being called a hero or being vilified in posterity. A stainless reputation also helps.