But the capitalists keep telling me our lives are great because now we have computers and cars and sugar in all our food! Don't tell me they lied to me..
the sugar thing just clicked something for me. I'm not exactly sure what it is that clicked, but often Dune's Melange is compared to oil. Melange spice is probably more accurately comparable to sugar, as sugar is a psychoactive substance.
Sugar causes a cascade of reactions in the body, with different amounts causing different effects and altering some people completely. Take diabetes type 2 - there is a genetic component to it, but it has been empirically shown to be a consequence of consuming sugar. Compare this to the Guild Navigator who becomes incapable of living in an environment lacking Melange because they've consumed so much of it.