You don't just take away privacy or decent wages or job security or healthcare all at once. You got to boil that frog.
Here in America it took us 65 years. This whole mess we're in started when Barry Goldwater lost. The corporate wing of the Republican party formed in alliance with the racists and the religious extremists. We were explicitly warned about it but we ignored the warnings.
That's one narrative you can tell. Another would be that the Republican party really only thrives when their candidates are brazenly corrupt and immoral. There's a fundamental dishonesty to candidates like Goldwater, Ford, Bush Sr., Dole, McCain, and Romney, who feel duty-bound to pretend to be moral while pushing the same aristocratic bullshit as Nixon, Reagan, Bush Jr., and Trump. I would argue that the latter were much more successful because of their shamelessness.
Constantly morphing coalitions consisting of odd couples is just the two party system. The right-wing pairing of racists and religious extremists is a much better fit than Democrats trying to get union members and the trans community to see eye to eye. The Venn diagram of racists and religious extremists is practically a single circle. One could argue that it was the Civil Rights Act that really got them to lock step.
Identifying a singular genesis for our current problems that can be articulated in a couple sentences sounds nice, but we can always move that back to something else. For example, "This whole mess started after WWII ended and the Cold War began, because the military industrial complex has made us economically dependent on a system incentivized to embrace fascism." Or, "This whole mess started when the Federalists and the Democratic-Republicans set the precedent for a two party system." One I like is, "This whole mess started when Truman's political cronies pushed him through as Vice President." How about, "This whole mess started when Joe Biden had the hubris to run for re-election and no one in his inner circle had the courage to vociferously insist he step down before the primary?"
History has no single narrative. It's complicated and messy. There are pivotal moments, but there isn't A pivotal moment.