I've been noticing the same trend with Tribe tokens; they start off worth something, then over a period the price starts declining, sometimes with a sudden initial drop. Once it happens, I've not seen any recover. So far, the only ones I follow that seem immune to this pattern are LEO and EDS.

It's frustrating, and I expect it is for the token creators as well. I'd love to know if there's a single consistent reason for it, but it is certainly starting to make me think hard about whether I should hold tribe tokens over the long term.