Except that Nintendo said that Switch sales were at 10 million on December 12th. https://www.nintendo.com/whatsnew/detail/nintendo-switch-sells-10-million-worldwide If Forbes and the WS Journal (owned by Fox News) are to be believed Nintendo magically sold 4 million more units for the remainder of December. Sorry but I'll take the more reliable source, Nintendo itself.
The Forbes, and WS Journal articles are nothing more than speculative clickbait, that ignore what Nintendo has already said.
When Nintendo announced 10 million, that was sell-through. Forbes' estimate here is for sell-in, hence why they referenced the 7.6 million figure at the end of September.