I think bounties, airdrops and giveaway are only option to make money from crypto without investment. Otherwise tell me, how can anyone make money without investment if he doesn't have hold any good altcoins what might make him profitable? Or no fund for trading! There is a way but lengthy process which is crypto related job! If you can develop your skill and knowledge about crypto, then many company will hire you for their projects. But it needs lots of times. But it helps you to make better future
Most of the bounties these days, airdrops are failing where even a few years ago it was one of the best ways to earn money without investment for many. Nowadays, the number of cheaters has increased so it is very difficult to expect to get money from such projects without investment. Time is running out fast without any hope of investing I mean clearly if you gain deep experience in crypto currency and also if you can create a source of income then you can invest your money earn profit from it.