Just for the sake of clarity, the Cardwell Reforms in the 1870s abolished the purchase and sale of commissions. The only exception to that was in the case of those wealthy enough to outfit their own units, which with some limitations they thereby gained the right to lead. A very rare event, but one in which there were some notable successes and almost no outright failures.
The Royal Navy had never allowed the purchase and sale of commissions and entrance was by competitive examination even in the 1700s. One reason the prestige of the Navy was generally much higher than that of the Army.
The truth about "the British officer" lies between the cliches, but in general their greatest weakness was their lack of training compared to some continental armies and the somewhat affected aristocratic distaste for "shop" and "professionals". An officer was expected to know how to control himself, his men and his horses and women(!) by virtue of his birth and education: "breeding" as it was called at the time. If he had to "study" those things he was probably not a gentleman it was felt! And of course when you tell a man from a young age that he has in the words of Cecil Rhodes, "won first prize in the lottery of life", it's not surprising how often that young man comes to believe it and to actually live up to it.
Their lives in the Victorian era were not without privilege, but compared to our modern lives, their service was harsh, unforgiving and very often debilitating, if not fatal. There was in general no molly-coddling of those who failed to behave as an officer and gentleman should, in or out of service. Valentine Baker for example was Colonel of the 10th Hussars, one of the most prestigious regiments in the Army, and a friend of the Prince of Wales, until he was found guilty of assaulting a working class woman. He was imprisoned, thrown out of the army in disgrace and left the country, never to return.
Say what you like about the officer class, but with few exceptions they had a much higher moral code than many people today, including many professional officers. They also knew how to die.
In this year of the centenary of 1914 there are many photos of WWI casualties, including many officers. Take a look, many of those men would stand out in a crowd today, and they were slaughtered in their millions. Their descendants are not with us for they were never born, and that friends, is the principle reason IMHO why we are where we are today!