Any profits made from investments go back into the charity's holdings. This is a good thing.

More specifically, I worry that Internet.org is an advertiser-funded competitor to the user-funded internet as we know it, and that the interests of advertisers are in many ways contrary to the interests of individuals (e.g. w.r.t. privacy).

Information pipes are a really important building block to a thriving political and economic ecosystem, and for those blocks to be sturdy, it's important that these pipes have built-in privacy protections which remove a lot of value advertisers derive from them.