Scams happen when people lose sight of the underlying product and blindly invest.
Unfortunately, this has been happening a lot these days.
It's greed. People have seen how Ethereum has gone up like there is no tomorrow after its public sale. People are trying and hoping to buy themselves in such a jackpot once again. That's why they just blindly put their money in certain ICO's without actually doing research. These people mostly find themselves being burned as of course only a very few of the ICO's will experience some sort of success.