It's a mistake to assume that Islamists always come from the slums. Indeed, many come from affluent families but for some reason just couldn't manage to integrate into Western society, even though they had good opportunities for advancement. ↗
Yes, Manila had its slums; one saw them on the drive from the airport: vast districts of men in dirty white undershirts lounging idly in front of auto-repair shops — like a poorer version of the 1950s America depicted in such films as Grease. ↗