just like every ICO, you risk more than buying after launch but with the chance of making much more profit. The risk of course lies in the fact that you are buying a "sealed" product and that you don't know how liquid the market will be and how it will behave. The big reward consist in the fact that if the coin is worthwile, it is likely going to reach a much higher value than ICO price.
I have personally taken part to many ICOs and I have always gained from them, the important part is to be able to read the market if you are just in for the speculation. Some ICO coins as shown have suffered indeed of a price dip after launch, but usually that has happened after the coins had been listed on exchanges at a much higher price than ICO price, so in fact you would have only lost potential gains if you bought during ICO, not actual money. Worthy examples are Ethereum, or more recently IOTA, which is not yet listed on any exchange but through private agreements and NXT asset exchange is traded at almost 25x ICO price after some months.