It's quite simple really. Once you go too far toward either extreme you unwittingly sow the seeds of the opposite to grow because the far-left or far-right only ultimately offers failure. People become desperate and see it all going wrong, so decide something resembling a major correction is needed to the opposite, but that's wrong and history has constantly proven this to be the case. You also have a constanly disillusioned youth every generation wanting change because they are constantly being screwed over too... which means they rebel easily. The answers are in the middle, and to be honest, whether you should be center-left or center-right depends on the topic, and different issues require different approaches... it's a beguiling myth that one side or the other offers the elusive answers to everything, but a powerful one. For example, when it comes to things like quality free health and welfare services for those citizens who need it or civil rights and freedoms, then we should be approaching those sort of things from the center-left... however, you need a robust economy to pay for it and strong emergency services/police and armed forces to protect it and your society, which comes from the center-right. Really, well-functioning countries have a mix of both sides depending on the topic/issue. You have to have compassion where fair and just, but also strength and will to protect it and do what's right for you people... otherwise you end up in the toilet, which is where Europe has essentually gone through falling foul of this. Trouble is, the longer you let it fester and worsen, the stronger the medine needed to fix it and put things back on track... hence rebellions, revolutions, sudden political realignments, or civil unrest happen. Politicians are spineless and just kick the can down the road, mainly because their terms in power are too short to really fix things, so why bother? Just ride the gravy power train and go down as a footnote in history instead of making hard decisions people want results on. Something is going to have to give at some point and it could be messy... people are becoming increasingly annoyed with what's happening.