The failed ones are recent which means the outcome has the potential to change in time.
Would an 80% success rate over the last hundred years change your perspective?
People who live in those places rightfully do not give a flying fuck about westerner's perspective. They care about being killed, maimed, displaced, robbed of the source of income etc. etc.
I can only imagine what would happen if you stood in front of them and tried to explain your stats.
Additionally I am not convinced that a independent Kurdistan would be a good idea.
I know Abdullah Öcalan has come under the influence of Murray Bookchin, and has had some very progressive ideas about how the politics of the Middle East should be structured. But in the event of the establishment of Kurdistan there is no good reason to believe it would be any less of a dictatorship than Iran, Turkey, or Dog help us, Syria.
Let's start with Italian fascism and Mussolini, financed by the US. Worked ok, everybody was happy. Next Hitler financed by the US. Worked ok, everybody was happy. Until their partners started to threaten Singapore and those pesty sunken ships. US and Britain suddenly not so happy anymore. Let's turn it around.
Next, coups in Turkey, Greece, ... and massive interventions in Italy and France. Military fascist dictatorships were of course great for their countries, and their people, esp. the workers.
Or East Asia. Japan's and Korea as prime examples but also most others, such as Indonesia, Thailand, Laos, Kambodia. Turned out extremely well for Indonesia and Kambodia, lots of dead socialists. Japan still ruled Korea via proxy military dictatorship, but everybody loved the new fascist systems in Korea and other proxies. A few thousand protesters were killed in massacres, but workers protests need to be fought hard, right? Socialism.
Latin America also loved their US coups and military dictatorships. The few socialists were tortured or flown out to the sea, and business could flourish. Happy times. Certainly the best system in the world. Freedom.
https://en.m.wikipedia.org/wiki/United_States_involvement_in...
From Costa Rica to South Korea to Japan to modern Iraq to Egypt in 1952 to Lebanon etc..
Iran didn't work out. Some of the central American operation didn't work out. Cuba didn't. But things are not static either. Things have a habit of working out given a longer timescale.