Technology is there. It's working. So not, it's not a scam.
And 2 years to develop a good working application isn't that much. 2-3 years is a time to develop working prototype.
Is it overhyped? Yes.
Most of this companies that got millions of $ from icos won't devliver product. But if couple will, then we are have proof that technology has it's use case.
RE: Is Ethereum a possible scam?