what you mentioned really happened to IOO, and lately ICOs have often been created but cannot deliver very much results and maybe the ICO now has begun to tend to go down and the interested ones have started to decline, and your choice to get out of This ICO is the best choice for you.
It is always good to get out from the ICO's because really the companies are raising the money but cannot able to deliver what they have promised to the community. So it is always good to follow the interesting project while after listing them in the exchanges and follow their development strategy until they deliver the end product.