It's probably the most common pronunciation among native speakers and it makes the most sense with like "soft before i" thumb rules and stuff like that ...

But it's stuck in my head that gyroscope should be /guyroscope/ and not /jyroscope/. It's even a soft g in Swedish, /yüroskawp/, so that's not where I'm getting it from either.

I guess I just have a higher expectation on English to stick closer to the Greek when it's a Greek root.