Average no. of Pakistani student per year : 10,000
Average expanses of Pakistani student per year : 15000£(fees)+5000£(expanses)=20,000£
Net Contribution to UK economy : 10,000 x 20,000 = 200000000£

We are a poor country, if we spend that much money on developing our own educational institutions and economy, we can get a better value out of this money. And, we won't be treated as terrorists and criminals.