How many chose to buy it?
It's the most bogus figure in the history of Windows due to the way they practically forced it on existing Windows users as well as the fake end of retail end user support for XP and then recently Win7. They are still supporting Win7, just not to the public, purely out of ego to boost Win10 deployments that they make little or no money from. Public updates to Win7 would cost them almost nothing.
Windows XP ended on April 14, 2009 and paid Extended support for desktop ended on April 8, 2014, however support and distribution of patches continued for years after that if you set that your XP was a POS terminal. You could ignore all non-security upgrades.
Win 10 is more about corporate Ego and being a Cloud Services client. XP (A fixed Win 2000) and Win 7 (a fixed Vista) were the last two decent Desktop OS from MS. Better to migrate to something else now.
Also they have practically abolished QA & Test. The Windows Insider program is a failed crowd sourced testing scheme. Corporate marketing and Cloud people have too much MS Control. In reality Win7 will be getting security patches for years. Just not to the Public.
POSReady 2009 (XP SP3) Extended support ended on 9th April 2019
Windows Embedded POSReady 7 Mainstream support ended on 11th October 2016. Extended support for Windows 7 ended on 14th January 2020
Extended support forecast to end on October 12, 2021. Likely will be extended. Paid desktop Win 7 support till at least Sept 2021