Quote from: JPMorganson on October 02, 2017, 10:39:11 PM

Scheme of Ponzi - Eng. Ponzi Scheme, is an investment scheme that provides the income of earlier investors at the expense of funds received from later investors. Initially, it may look legitimate, but the Ponzi scheme usually collapses as soon as the inflow of funds from new investors becomes insufficient to make payments to the old. In some cases, the Ponzi Scheme scheme is initially used without malicious intent, but in order to make a profit with the fulfillment of all obligations to investors.

So it clearly defines an investment is opposite to airdrop which is no money from your own pocket will be invested so definitely airdrops are not related to ponzi schemes its just a free giveaways from devs its just an act of generosity nothing else.