Geroge Orewell in most of his life was a very altruistic person and it's because in his day he grew up in a world that seemed pretty bleak and dark as the bottom of the ocean (much like today). He saw World War 1 and how damaging it was because the former European the Muslim empires destroyed themselves and the lives of innocents in the name of their own ego. He grew up during the post-Industrial Revolution era where big rich fat cats would take advantage of others and even playing any weak governments like fools while brutally exploiting their own workers even if it costed workers their lives (in the days of the legendary monopolies such as the Standard Oil Company, a person's life was worth pennies because workers were that expendable). He saw how men, women, and children of the most lowest social class of England would gather together and voluntarily go into the rivers and lakes being contaminated by the factories that poured in their hazardous waste into the once clean waters where people would try to dig in the murky waters for valuables that they can sell to have food and something to drink on the table because they weren't given as many opportunities to better their own lives anyway.
The life for Orwell in his day seemed pretty dark so naturally Orwell, like many people in his day, he became a commie and he thought that Communism was the answer to humanity's problems and it seemed like things were going to get better as this new idea known as Communism seemed like the hope for the bleak world he lived in. Well he was proven wrong when the USSR went from being a spark of hope when Lenin was in power to a nightmare when Stalin came to power and this is where he started to question his own beliefs.
When the Spanish Civil War happened (which he joined because he genuinely believed in the cause and actually gave a damn about Spain having a secular government), he would become disillusioned with Communism from this point on once he saw how toxic and non-productive many of these stupid commies were and this is where he pretty much realized that his far-left beliefs that he held at the time aren't that much different from the beliefs of the imperialist monarchs of old then.
The only reason why George Orwell still remained a leftist in his final days of life is because truth be told, he actually had principles and stuck by them unlike many of his fellow leftists that only get into Left-Wing politics for money and power. He still believed that the world can get better if humanity would just put aside their differences and worked together for the common good and wanted the world to be a better place, he truly believed that humanity could better itself if people sat down and worked together and that kindness and love prevailed over darkness and hate but sadly many of the leftists at the time (like now) were never like George Orwell and he was greatly disappointed to see his fellow leftists care about themselves than actually bettering society per se.
Had George Orwell was alive long enough to see the rise and the demise of the Hippie movement that was prevalent in the 1960's then he would have most likely been totally disillusioned with Leftist politics altogether once he saw just how violent and hypocritical the boomer hippies were and Orwell would at least probably become a centrist by that point. Geroge Orwell, truth be told, was truly a kind soul that only wanted the world to stop destroying itself and get better but sadly the rest of the world didn't wanted to show the same kindness like he did anyway.
