Well no one claimed that ICOs were magical endeavors and all of them would succeed. They are pretty much no different than other, standard business: If you don't have a working product or are not addressing a specific need, you are not going to make money selling that product. Even if you succeed initially (off of hype or whatever), eventually you will fall down on your face.
The same applies to ICOs, and I'm surprised the ratio of failed ICOs is not higher, to be honest.
I know right? I thought the % was like 90% of ICOs fail, but like you said, If it's not usable, then why is it here?
Well they try to make money however they can. Since ICOs are not established yet, there isn't an established opinion on the part of investors as well. Most regard ICOs that will multiply their money by 50 magically, so most invest in whatever they see without looking into it. Some industrious people try to capitalize off of this by launching an ICO and trying to create hype, although their product is worthless.