From Wikipedia:

"77% of Crimea's and 94% of Sevastopol's population are native speakers of Russian"

In April 2014, Ukraine passed a law that effectively banned Russian as an official language in Ukraine. Prior to that, Russian was enshrined as the second official language in Odesa, Kharkiv, Kherson, Mykolaiv, Zaporizhzhya, Sevastopol, Dnipropetrovsk, Luhansk and Donetsk regions.

In Crimea, Russian was always an official language due to Crimea’s peculiar history and its historically independent/autonomous status.

https://www.opendemocracy.net/en/odr/ukraine-language-law-en/

Does it not make sense that speaking Crimeans would want to join Russia and secede from a country that was outlawing their language and culture?