Meanwhile (since 2012) Trump happened, race unrest's, police brutality, corona handling fiasco, Google/FB/Amazon public image is going down, USA public depth has roughly doubled [1] and general perception of USA has changed (to the worse[2]), China is hiring, student depth is going trough the roof (and immigrants want to have children someday), no one believes in "war on terror" any more (talking about EU), Snowden, war on privacy,...
This graph is outdated, did you find some that is up to date? Also interesting one would be how many of those in 2012 survey stayed and where.
[1] https://www.statista.com/statistics/187867/public-debt-of-th...
[2] https://www.pewresearch.org/global/2020/09/15/us-image-plumm...
But since you did bring up Germany with the deleted mention of Operation Paperclip, I suggest you read https://news.ycombinator.com/item?id=25367731 , in which @bildung and I discuss German migration to the US over the past 30 years (including 2019 data).
I provided statistics in response to your anecdotes. The onus is on you, not me, to prove that a) your anecdotes are actually representative of broader trends, and b) my statistics are, in fact, outdated.
Now let me give you actual statistics.
In a survey of scientists from 16 countries (http://spectrum.ieee.org/at-work/tech-careers/the-global-bra...), the US is the top destination from 13 of the 15 others and the #2 choice from the other two.
By comparison, only 5% of all American scientists move to another country, of which 32% go to Canada.