What if Hitler had been promoted to the rank of Captain during WWI?

Adolf Hitler was a well-educated, articulate, well read and likeable young man, who served with distinction for four years in the trenches of WWI for the German infantry. Why, exactly, did he never progress beyond the rank of corporal? I believe the reason for this is that Hitler was deemed indispensable as a messenger, and being a messenger was such a high-risk job, that soldiers beyond the rank of corporal were deemed too valuable to be risked as messengers. So, Adolf Hitler, who seemed to lead a kind of charmed life and be effectively indestructible, was seen as the perfect messenger and was never promoted to sergeant, or beyond. Why promote him? Nevertheless, I do think it is perfectly possible that Hitler might have been promoted at some point. And, if he ever had been, he might have risen rather rapidly in the ranks, perhaps as high as the rank of captain, by the end of the war. If this had been the case, Hitler would have had experience of strategy and tactics in warfare that he never really had until the second world war, as the Fuhrer of Germany. Hitler would also have been immediately qualified, as a distinguished German military officer, for positions of considerable administrative authority in Germany at war's end. So, his post WWI career is likely to be quite different than what it actually was, OTL. He may never do much public speaking at all, being busy with administrative activities. He might end up as a successful civil servant, just like his father was. Or, if Hitler does indeed pursue public speaking and politics, despite his higher rank, he may have a more realistic appreciation of his limitations, and of tactics and strategy, from his experience of actually leading men in the field, something he never actually had OTL. Hitler's willingness to take on the British Empire, the USSR and the USA all at once OTL, despite the fact that Nazi Germany was quite incapable of defeating any of them individually, probably stems to some extent from his near total ignorance of even the most basic principles of tactics and strategy, which even a year or two's experience leading men in the field of battle in WWI as an officer would certainly have given him some smattering of. If he had become a politician, I suspect Hitler would have been a more pragmatic one under these circumstances, and much less of a risk-taker and a revolutionary. Hitler is generally considered to be the essence of evil in most of the world these days, but, actually, until he fought in WWI, he was just a likeable eccentric. His life course represented an unusual combination of talent, ignorance, and astonishingly good luck. It is amazing that he survived WWI physically unscathed, in his first action of the war he was the only one of six hundred infantrymen to survive. And he pursued suicide missions throughout the entire war. So, he developed incredible self-confidence, and, a sense of mission. Nevertheless, he was not a self-aware person, and his life experiences were limited. So, he had no sense whatsoever of his own limitations. Was Hitler "evil", or, was he just ignorant? So, supposing Hitler had been promoted to captain during WWI? What would his subsequent career have been like?