Isn't this a good thing?
We want to train highly skilled people and then unleash them in the private sector to create new companies or help push existing companies forward.
I'm not sure what the right percentage would be for postdocs leaving academia, but i would have assumed it was around 90% if you made me guess.
That just seems healthy.
> We want to train highly skilled people and then unleash them in the private sector to create new companies or help push existing companies forward.
Many of these people will become very frustrated in the private sector because they will very commonly talk to a brick wall with their ideas in the private sector. The private sector is commonly not the kind of environment where highly intelligent, novel, bright ideas are rewarded.
I think you are conflating postdoctor with degrees like masters and bachelors, surely?
> We want to train highly skilled people
After how many postdocs is one "highly skilled"?
Postdocs are foremost a failure of the academic job market (supply of eager researchers much larger than available academic positions) that over time has become some sort of ingrained filtering mechanism.