I don't know if the nihilist needs the idea of infinity to generate the cynicism. What's needed is the scientific objectification that discovers nature's inhumanity. The conflict is between the self-serving intuitions that drive our civilized projects, and the cosmic environment that's indifferent to the smallness of those intuitions. The universe may be finite, but it's still fundamentally inhuman, whereas social mammals like us are mainly self-interested socializers. And socialization looks ridiculous in the cosmic scope of things.