In a third world country usually the salary is low. It can't cover most of their daily need. Bitcoin is one alternative way for them to get extra income. And believe it or not, this extra income could be greater than their montly salary especially at bitcoin's current price.

Participate on a signature campaign and another bounties that being held in this forum is one of the most common thing to do to earn bitcoin/altcoins. But, it's not free. We have to invest our time and efforts to eligible to gain the bounty.