The first is the advent of massive wealth on a scale never seen in human history. Yes, we had Gilded Age robber barons who amassed riches and skirted beyond the law. The Progressive Era at least attempted to rein in those malefactors.
The second was telecommunications. When Madison Avenue discovered the previously unknown power visual telecommunications held for influencing the human psyche, they struck gold. They were able to amplify the most selfish of human instincts and reconfigured our cultural norms to an extent that unfettered consumption and materialism was equated with our most idealistic foundational values. It was a seen as "un-American" to throttle egoistic avarice. Intellect and self-determination fell even further behind in its race with consumption as a governing force.
That same greed leaked into our Fourth Estate and ruined it. That had an effect on society as well.
When we made the jump to pocket computers, Americans no longer had to unplug from the propaganda to go about their daily business. Not only could they stay engaged, but the inevitable isolation from their immediate communities had an impact.
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