Bro in my point of view bounty campaign are the best way to earn crypto currencies as this is the least risk involving method or I should say that this method involves zero risk as you need not to invest your money into crypto as in this you only work for them and in return they pays you for your work and rest other methods I know to earn these crypto are either you work as a free lancer and they will pay you or directly invest into crypto by purchasing them in exchange of your money.