Require all people who received higher education to work for their country first for 15 to 20 years.

There's no point in being able to buy an outrageously fancy toilet with remittances if there's no sewer to hook it up to.

That would be a great way to make the brain drain even worse.

That would discourage higher education, you are basically punishing people for it.

Try giving free education to all government employees instead.

Discouraging higher education, IMO, isn't a bad thing. Academia is too much of a walled garden that is too easy to enter.

This resulted in higher ed becoming a defacto requirement for many professions that could have been open to professionally trained or experienced people. Employers need to draw their baseline requirements somewhere and if expensive credentials are too ubiquitous, it's understandable they rather select from those who achieved them than from those who didn't (or couldn't afford to).

And it's frankly disgusting how many doors remain closed to yourself unless you got access to an .edu email. More people with academic interests not having acquired one might open the door to many more who discovered their academic interests later in life but can no longer find a way to enter that garden.

Same approach China is taking -- harsh penalties + heavy press broadcasting in the most egregious instances uncovered, with an emphasis on consequences for the high ranking folks involved.

You don't want to try to catch everyone, as then people do worse things trying to cover their tracks, but you do want to establish a credible fear of consequences that will shift the default societal balance point between {do corruption} and {don't}.

And it may take a generation, but it is possible.