The turning point

While this meme is simplistically reducing the turn to the tax cuts in themselves, that was indeed the turning point. The cuts started the cascade of related events that decimated the middle class. 

As just a few examples, it allowed corporations to give all the extra money to their owners and upper management instead of investing it back into the business and employees. The higher tax rates forced them to do the latter in order to write off those investments to lower their effective tax rate. With the cuts there was no longer any incentive for that behavior with the result being stagnant employee wages, benefits and degeneration of the business infrastructure that supports win-win situations for all involved. 

But hey, memes are supposed to be short and catchy to affect us, and that long explanation bores most of us.