From 2005 to 2015, Haidai was the General Director of Dembud LLC.[5] From 2008 to 2010, he worked as an Assistant Member of the Kyiv City Council.[6] From 2014 to 2015, Haidai worked as an Adviser to the Chairman of the Obukhiv Raion State Administration.[6] In 2015, he was elected a Member of the Mukachevo Raion Council.[6] From 2015 to 2018, he served as Chairman of the Mukachevo Raion State Administration.[7]
During the 2022 Battle of Sievierodonetsk, Haidai observed that "The Russians are using their Syrian war tactic in Sievierodonetsk. First, they try to raze a few kilometers of area with air and artillery fire and advance with ground troops. When they gain strength, they retreat, and start shooting with long-range weapons. On the other hand, when they start hitting with cannons, we retreat and then return to our positions."[citation needed]