Why on earth are binoculars pronounced as /bɪˈnɒk.jʊ.ləz/ instead of /baɪˈnɒk.jʊ.ləz/?

Solution 1:

It comes down to the prefix. It isn't bi- but bin-.

Bi-ocular would be pronounced /baɪ-/ but binocular forces the harder /bɪ-/ sound

Updated to articulate what @Reg said below - it's around where the stress is - Bin is the stressed element of this word.