That means they are spending a lot of money they earn on the local economy itself no? So even if their taxes are higher, if they are creating value in the economy, the locals do end up seeing those benefits imo.

From the perspective of a someone in country that loses a lot of talented/educated citizens to brain drain, If i were in charge of a country to which high skilled immigrants flock to - even if it is for a limited time, I'd try to see what I can do to convert them to permanent residents. It is a tricky thing to balance because the locals shouldn't feel like second class citizens in their own lands. But at the same time, if skilled people are migrating away - that's a lot of missed potential/opportunity.