Picking up on Sammy's point, there isnt work available all year round so they need to earn enough to see them through off season. I don't like greed, but no-one is forcing us tourists to give tips etc. Personally if someone badgered me for money they wouldnt see me for dust.
However when you look at how hard they work, taxis on the go from early morning until early hours next morning, waiters much the same, beach sellers slogging up and down the beach day after day and then working the night markets. Its hardly suprising they are looking for an occasional hand out.
I can only speak from personal experience, I only know of one person in 14 years who 'ripped me off' it was only a few pounds but it made me mad and they never got anything again.
The rest of my friends, none went to school they worked the beach during the day, they can't read or write - some now have kids of their own. They all say the same thing, they don't want the same life they had for their children .They are putting them through school not sending them begging on the beach as they had to do. They should be commended for that.