You're right that condensed matter (or other sections of physics outside high energy) is not a likely place to find new fundamental physical theories. The comme

You're right that condensed matter (or other sections of physics outside high energy) is not a likely place to find new fundamental physical theories. The commenters are instead arguing that there is a lot of space for new discovery within our existing fundamental theories. That doesn't mean this work isn't exciting or valuable; this kind of work includes things like quantum computing (most of which falls within condensed matter). If understanding the ground rules meant you understood everything that can arise within them, math would be boring by definition since we generally choose our ground rules in mathematics. So we're still finding interesting and unexpected things in other areas, including fundamental rules that are non-obvious features of existing theories (theoretical quantum information work finds new things here all the time). So for people in high energy that like finding new fundamental facts about the universe, this is a good place to go. Some methods developed by string theory and other unification theories are actually already used in condensed matter!