WTF is up with Luxembourg on that graph?
It is a tax haven, with one of the highest GDP / person in the world, why is it, by magnitudes, the biggest recipient of EU largesse / person??!
I presume this is because of the EU institutions there and that expenditure to maintain those institutions counts towards receipts (and this effect is then exaggerated due to Luxembourg's small population). Certainly no one in the EU is under any illusion that Luxembourg is poor, much less vastly poorer than the next poorest EU country.
Notoriously difficult to portray correctly in EU money-shuffling statistics. Some money not granted to the grand duchy still filed under "beneficiary country: Luxembourg" due to some program or institution being headquartered there. And it is essentially impossible to compare apples to apples what happens in actual EU budget and what happens in Kirchberg, home to EIB.
Small population plus lots of EU institutions.
Lots of people who work in Luxembourg don't live there so anything "per capita" is a bit misleading.
Additionally a lot of the EU's institutions are based there or have offices there, some of which might count as investments as well.
Lastly, everything there is really expensive. So you need to invest a larger amount to achieve the same thing as elsewhere.