Arroyo is in the mould of Tony Blair. Pretends to be the real deal but deep down she's just the typical self-serving politician who's main goal is to feather her own nest. Actually, she's regarded by some as the most corrupt of all Philippine president's.
Unlike the rabble beforehand (with the odd exception), Duterte genuinely cares for the people of his country, although I'm not sure if he's going about it the right way.
I think the main reason is why people turn to drugs is out of sheer boredom. Individuals who don't work have around 16 hours per day to occupy themselves and that's a long time each day. What have they got to do? If they're lucky to have access to the following - basketball, karaoke and to watch crap on TV featuring Vice Ganda & co. The latter itself is enough for anyone to turn to drugs.
It'll be interesting to find out what Duterte's next plan of action is.