I could've won this if I had earlier...
That is, I made a wrong choice. In this MV DA game crippling difficulty gigantic galaxy: me (Altarian Resistance), Korath, and Terrans were remaining after starting with 9 races.
I retired when Korath declared war on me (I am the light-blue line in the graphs). The Terrans and Korath were close relations to each other and the Terrans were neutral while I was evil - so there was no hope of help against Korath.
Earlier Korath were "close" but I did not attempt an alliance (I didn't trust them). The Terrans were "close" several times during the game, but would not accept an alliance for any price. At the end they were only neutral relations towards me.