Crimea only went to Ukraine, because Khrushchev, wanting to make nice with the Ukrainians after being Stalin’s man in Ukraine, made the meaningless gesture of transferring Crimea from the Russian SSR to the Ukrainian SSR.
We should recall that the Russians signed an agreement with Ukraine for the use of a naval base until 2049....and that under that agreement...Russia was allowed up to 24,000 troops in Ukraine.
.... At the time of the illegal coup in Kiev they had roughly 16,000 troops stationed there. The Russians moved to insure that there military assets weren’t used against either them or the Crimean people.
Given the rampant corruption in the Ukraine...I can’t say I blame them... At this point the Crimean people were given a choice...take their chances with an ‘openly hostile’ gov. to Russians in Kiev...or return to Russia, which they had been a part of for more than 2 centuries.
Given that the vast majority of Crimeans are ethnic Russians...it’s no surprise that they chose the stability and familiarity and voted to return to Russia...... further we certainly know now that Ukraine/Kiev was the illegal coup d’etat started with the financial and logistical help of the US...