It is best to buy those tokens that will give you a profit in the future, and now no one in the project uses the PPI, everyone has gradually switched to IEO, but everywhere there is a final development of the minuses, but I found a project that will later make money
https://bitcointalk.org/index.php?topic=5136520This is how I understand they work through the IEO system? since in general there are almost no old habits on the market