Short answer, already said here: the ethnic base born into it. Here in their Slavic, industrial home base in America, the Northeast and particularly Pennsylvania, they're endangered (here in Philadelphia they're fewer than upstate), dying, but anyway, they are what they are. After the two waves of conversions to the Orthodox circa 1900 and in the '30s, they have their essentially Latin Catholicism with a modified Eastern liturgy and don't identify with the Orthodox at all. That and the experience of the WWII refugees who are the backbone of some Ukrainian Catholic parishes, the first Eastern Slavs I knew (30 years ago); the Soviets banned their church and tried to herd them into Orthodoxy.
Converts: sure, the ones online often are passing through to Orthodoxy. As has been written here, they want to do what Rome happens to tell the Eastern Catholics to do, be just like the Orthodox liturgically and express Catholicism in Orthodox terms, then they get fed up when they run up against the reality I just sketched above.
Offline you get a mix among the convert minority: born Roman Riters who fall in love with Orthodoxy but have nothing against Catholic doctrine, the online 'Orthodox in communion with Rome' who've turned against post-schism Rome and understandably soon leave, and refugees from Vatican II/the Novus Ordo going to the only sound Catholic church in town. They've become the majority in some Ruthenian parishes, keeping them from closing.
Ukrainian nationalism = the Ukrainian Catholic Church = old Polish Galicia, one of the places the immigrants 100 years ago came from (the other being Ruthenia, their cousins) and which Stalin stole during WWII (ditto Ruthenia, but WWI basically ended Ruthenian immigration*; they're Americans). The rest of the country's like Russia proper, Russian-speaking (everybody from Kiev I've met) and Sovietized secular but with a minority of practicing Orthodox.
Greeks and Russians likely won't pressure you to convert; they have nothing to prove. They're happy being Greek or Russian and understand if you're happy being Irish or Italian Catholic, etc.
*Got to talk to a living treasure while she was still with us, a Ruthenian immigrant who happened to come over after the war. She described her home area, then part of Poland like Galicia, as it was in the '30s. 'We were all Greek Catholic' but for some reason she ended up Orthodox (marriage?). Village churches with miraculous shrines the people would walk on pilgrimage to.