An ICO that drops flat to zero s definitely a big scam that never got into the market in the first place. No matter how bad an ICO does, without a product or use case, and it gets into the market, it should be even at the leat price, not completely zero.
Good projects never die no matter how bad market circumstances affect to their development. Price falls to zero in case of dead liquidity and i have heard about one project which CEO passed away.