I said CHINESE not Mandarin.
This is getting more and more off-topic but I'd argue that "Chinese" is not a language. Mandarin and Cantonese are not mutually intelligible. This makes them less related than say Portuguese and Spanish. Up to the early 20th century, Mandarin wasn't yet made the official language of China, and in the not-so-distant past, "China" was a fractured sub-continent with dozens if not hundreds of distinct ethnicities, cultures, and languages.
At least in terms of people of different countries attempting to communicate with each other through a intermediate language, English dominates. And using "by far" to describe its prevalance is accurate and might even be an understatement.
But, back to the topic, I will never fault an athlete for choosing not to communicate in a language uncomfortable to them. Shohei Ohtani is probably the biggest star in Japan and in the MLB, and he chooses to use an interpreter despite the fact that he does speak English pretty well. These athletes have a lot on their minds, and the mental burden of trying to avoid verbal gaffes and mistakes on top of being at peak physical performance doesn't seem worthwhile.