It’s 17.7% of the people of the 25k people taking part in the Navigraph survey, which are probably the most hardcore simmers.
The sample size of the Steam survey is in the millions, and of those only 1.7% have VR headsets. If Steam has a 100 million users, that could indicate there might be around 2 million PC VR headsets in active use, but not everyone is a flight simmer.
So, yeah, the number of VR users of MSFS24 is probably in the tens or hundreds of thousands. At least one magnitude smaller than non-VR PC and Xbox users.