the money needed to be distributed to all bounty participants alone is not small.let alone during mining.
Those ICO project needs money to pay the bills of everyone that has worked for them in campaign and any other.
And aside from that they need bigger amount to sustain and implement their project. The main purpose of having an ICO is to invite investors to invest their project because of certain reaons such as good potentials and has a good team backing up, but sadly we cannot avoid the fact that there are some who are taking advantage to this kind of business such as some fraud projects or as we said scam projects.