Hmm, I just had a quick look at direct flights that same day and there was one flight leaving Zurich at 11am (which I’d never make on time) and another at 8pm (which would be fine - same time as the night train, too)
However both these flights were approx $270 usd, which is still more than the €189 for a single sleeper on the night train..... and I’d still need to muck around getting my bags then making my way to accomodation in Zagreb at 10pm at night, and have to pay for the accomodation too.....
I think I probably won’t have quite as good a sleep that night, as usual, but it’ll still probably be much easier (get on at Zurich, get some sleep - broken or not- wake up and then hop off in Zagreb).
Plus it’s only one night out of an entire trip, and it’ll be a bit of an adventure, an experience that I wouldn’t have had otherwise 😊 which is part of the fun of travelling 😊