I want to ask how does the people that do bounty make money.I mean they are giving away money for free.How is it profitable for ICO teams?
Because very less amount of people invest in their ICO through bounty.

Advertising through bounty is profitable because you are like a regular employee who will be paid according to the rank in the bitcoin forum. Most of the bounty needs an account of someone in order to advertise and endorse their company and token and through that it attract and encourage other people to invest in their ICO.