Why is the sentence without the verb in Turkish correct? I find it confusing! Although it is easier! Would ' bu spor çok populerdir' be correct or wrong or just sound strange?
If both are correct, where do I use them? Formal, colloquial?
Both are not correct. -DIr is used for encyclopedic facts or strong assumptions. This is neither of those. :) Turkish does not have a real verb "to be" in the present tense (this is especially true in the 3rd person, like this sentence)