Why Kazakhstan Was Most Supportive of Continuation of USSR

After Belavezha Accord was signed, Yeltsin and the crew had to placate Kazakhstan that everything will be alright, and they were the last to agree to dissolution. Kazakhstan was one country that mourn it actually. More than Russia itself.

Russia came up with Belavezha accord after Ukraine voted for independence. Belarus agreed only after Russia. Kazakhstan then for two weeks argued with them, they should not do it, but they were the only one at that.

Kazakhstan probably benefited from USSR existence more than other places in the Union.

Before Russian conquest of Central Asia, all the development was concentrated in what is now modern Uzbekistan. Then Russia, but especially USSR went to pump a lot of development in Kazakhstan instead, draining some from Uzbekistan in process, letting Uzbekistan to get dilapidated and overpopulated.

Because of that Kazakhstan felt all cozy in USSR, but was worried that without USSR, Uzbekistan will come to claim domination over Central Asia once again.