with regard to investment, it is quite logical - to make a profit. You can achieve results in several ways: first, the bonuses described above, and second, the increase in the price of Troy gold products.
I would also add to this also referral programs, a bounty campaign and a free contest. By the way, for some reason I always liked the referral programs more.
I assume that you like to invite friends to those projects in which you participate. I heard that the referral program gives you the opportunity to earn Ethereum and another 25% from Troy Vault.