It's not self fulfilling if it's accurate to begin with. I assume that what you are trying to say is that they became to pessimistic at the dismal state of affairs and "gave up". But that is not the case at all. Our progress as a species is faster than ever in every account and that is the problem, we are going very fast an the errors we make have larger consequences as a result an we have less and less time to fix them.
The first step to solve a serious problem is to diagnose it correctly. You cannot lie yourself out of a bad situation. The "relativist" as you call them or "realist" as I prefer to call them did their contribution by identifying the problems and setting up a framework to do so going forward, now is up to the rest of society to solve them. That is perfectly within our grasp if we stop pointing fingers at each-other and get to work.