I have some IOTA and have been holding it for a while because the project is very interesting indeed. But one thing that has bothered me, and keeps bothering me, is that I can't find a decent answer to the question: What is the IOTA token used for and why is it valuable?
Where will the demand for this token come from?

With Ethereum for example, ETH is the fuel and presumably this is used on smart contracts through transaction fees. But since IOTA doesn't have transaction fees, what benefit or value is there to holding IOTA?

Once I have this answered I will feel much better investing more into it.