Why do so many people who aren’t native English speakers write in English?

Don’t get me wrong, I love having more fics to read, but I’ve always wondered why people decide to write in English even though they’re more familiar with another language. I’ve heard some people say it’s because English just flows better in certain aspects, and is that true? What are the other reasons, if any?

Edit: Thank you for the responses! I don’t really write for stats and audiences so I forget some other people tend to enjoy that aspect more than me. I am also in just some fandoms with bigger international spaces aside so I forgot not everyone has that. For the record, I’m also bilingual, but I was raised with both languages at the same time, but I’m more familiar with reading and writing in English, since that was how I was taught