Reddit, 4chan ... as a source! I'm personally suspicious.
For the PSVita we have some official figures of its sales at the beginning of its career.
1.2 million on 25/02/2012
1.8 million at 31/03/2012 (the 1.8 million were not included in the 2011 fiscal year)
2.2 million to 30/06/2012
These were the only times Sony communicated officially.
Otherwise we know that for 2012, 2013 and 2014 Sony combined PSVita sales with PSP sales in its quarterly reports.
FY 2012: 7.0 million
FY 2013: 4.1 million
FY 2014: 3.3 million
That's a total of 14.4 million for these 3 years (PSP+PSV).
We know that the PSP had sold 76.4 million up to 31/03/2012. With the 82.5 million (LTD) that gives us an extra 6.1 million between April 2012 and the end of 2014, leaving 8.3 million for the PSVita during the same period.
Adding the 1.8 million during fiscal year 2011 makes a total of ~10.1 million as of March 31, 2015.
And from fiscal year 2015 onwards, it was only selling well in Japan, while in the rest of the world its sales only plummeted catastrophically, to the point of no longer covering the tracking of its sales from 2017 onwards.
And sales in the rest of the world were too low.
Code:
Euope (CESA)
+--------+---------+---------+---------+---------+---------+----------+----------+
| Year | UK | Germany | France | Spain | Italy | Nordic | Benelux |
+--------+---------+---------+---------+---------+---------+----------+----------+
| 2015 | 60.000 | 20.000 | 30.000 | 60.000 | 10.000 | - | 10.000 |
| 2016 | 20.000 | 1.000 | 30.000 | 20.000 | 10.000 | 10.000 | 10.000 |
| 2017 | - | - | - | - | - | - | - |
| 2018 | - | - | - | - | - | - | - |
+--------+---------+---------+---------+---------+---------+----------+----------+
| LTD | 740.000 | 350.000 | 500.000 | 450.000 | 290.000 | 110.000 | 170.000 |
+--------+---------+---------+---------+---------+---------+----------+----------+
America (NPD estimates NPD)
+--------+---------+---------+
| Year | USA | Canada |
+--------+---------+---------+
| 2015 | 280.000 | 30.000 |
| 2016 | 60.000 | 10.000 |
| 2017 | - | - |
| 2018 | - | - |
+--------+---------+---------+
| LTD |2.440.000| 260.000 |
+--------+---------+---------+
Asia (Media Create estimates)
+--------+-----------+
| Year | Japan |
+--------+-----------+
| 2015 | 1.069.471 |
| 2016 | 849.669 |
| 2017 | 344.813 |
| 2018 | 177.720 |
| 2019 | 28.968 |
+--------+-----------+
| LTD | 5.994.568 |
+--------+-----------+
When I see all this, I highly doubt it could have ended up at more than 16 million.