Well a lot of times the token has a utility in whatever ecosystem it is designed for so it has value. If the demand for that service increases, then the token value increases - hence why people invest. It's like instead of setting a static price for a product / service, you let it free float. If the product / service is in high demand, price will rise. That's how most tokens work.

Steem is an interesting case study. The incentive to buy Steem (and vest it) is to become a stakeholder in the platform (as the network of Steem applications grows, Steem becomes more valuable) and to gain influence on said applications. Of course, we don't know how this will work over the long-term. But it is one of the only solutions I've seen so far in an attempt to monetize social media content without ads. If abuse could be stunted, I'd be much more bullish than I currently am.

Thank you for the comment and hopefully some of my future videos clarify any further complex concepts.