The R&D centers in China (I think there are 3 of them) are their competitive advantage - this can help them manage cost to be profitable from early on. I also think the engineering teams there can share with their peers of the other local Chinese tech firms. For example, China was literately put in lock down in February, and all of the business and schools went on-line in couple of days - that was a enormous achievement for anyone who participated the scaling infrastructure at the big tech companies in China, and I would not be surprised that the Zoom engineers in Chinese R&D learned couple of lessons from them. Zoom even has a feature that you can choose to "soften" your appearance to look "better" in the video conference, which has been feature of camera/image software popular in Asian market. So I suspect their product team may also have some connections there.

However, Zoom's biggest advantage is also its biggest risk, if they want to be part of the communication infrastructure of any business/government/university/etc in western countries, especially after so many security incidents that happened in the past years.