Presale is a fundraiser organizer by developers before ICO, and the goal is to attract investors by giving bigger bonuses. Presale with bigger bonus just like marketing strategy. But with the bigger bonus given will also be followed by high risk if after ICO finished the hard cap not reached and the project get failed. So it is very important to study the white paper and other fundamentals of the project before investing.
That's exactly what it is - although there are some ways to mitigate the risk for the very early pre sale. We are using an escrow service and contracts so that if the pre sale doesn't raise the required funds then everything will be returned via the escrow service. Still risky but there are a few things that projects can do to try and de-risk the opportunities