On one hand, the white paper makes mention of the fact that it works like the lottery, in that people tend to expect greater returns then they'll actually receive. So on that point, I agree with you.

As I see it, five (or more) things can cause STEEM to continue gaining value: (i) growth in numbers of steemit users; (ii) improvement in web-site usability/user engagement; (iii) improvement in quality of content and curation; (iv) New applications making use of STEEM; (v) Actual purchase-demand for STEEM. As long as one or more of those areas improve, I think STEEM should be able to continue gaining value.

When you buy steempower, it's an investment, but it's also a tool to amplify your voice, so it's not too different from buying advertising in other environments.

In the end, the web site merely provides a mechanism for people to do the same things they're already doing for free on sites like reddit and facebook. With a new business model and a new cryptocurrency, it's certainly a very speculative and risky investment, but if STEEM/steemit is a scam or a pump & dump, then I guess facebook and reddit must also be.