Boring, in short. As with the other great apes, indeed with any social grouping in any species, you will get hierarchy and dominance.
You are presenting violent extremism as the inevitable consequence of hierarchichal societies - and to an extent you may be correct. But for the large majority of people living withing virtually every society on earth, be it democratic, communistic, theocratic, repressive, open, or otherwise - violent extremism is not the answer or the solution, so not all societies will fail as a consequence of such action. When was the last leader of the UK assassinated? or of Germany, or France, or Sweden, or a host of other countries? You appear to have a rather bleak view of life - you need to put on your antic pants and get out more ;)