hmmm … You mean, Younis Khan with his family lives in Karachi, left Pakistan cup in Faisalabad and moved to his home city Karachi, because Karachi gives him more opportunity … specially when it is on record that younis Khan learned cricket in Karachi and his mentor (Rashid Latif) told him that if he keep playing in Karachi he would never get into national team, so he moves to KPK for better opportunity in Pakistan national team?
Shahid Afridi lives with his family in Karachi for better opportunity, when it does not matter to him today weather he lives in Karachi or anywhere, rather he would have more opportunity if he moves to Lahore, as racially bias management in PCB prefer players from Lahore and surrounding areas.
You mean, a labourer from FATA and KPK, who has plenty of opportunity to find job at much closer places like Islamabad and north Punjab, still move to Karachi full of deteriorating roads, bridges and transport system? …
Why is that, when logic says that Pakhtuns from Karachi should start migrating to north Punjab, as most honourable and respectable Shareef thugs (NS and SS) are spending every government resources left over from their looting and plundering, on roads, bridges and other construction in area they belong. So, why it that happening? Why even today Pakhtuns prefer moving to run-down Karachi than upcoming northern Punjab? Do Pakhutns also have brain like you … ignoring the obvious? 
I mentioned few cases, but there are number of names I can take, who showed preference to Karachi than other places in Pakistan, not just because of opportunity, but because they consider there is no discrimination in Karachi … rather fact is that, when it comes to Karachi government jobs, people of Karachi gets discriminated.
Unlike Karachi, I doubt Lahore or any city of Punjab would have tolerated over 90 percent of police force from outside Punjab, or huge number of employees in any Lahore government departments from outside Lahore, while knowing that many Lahories are struggling to find jobs.