In the US today, you're a real dumb dumb if you try to attain power via a left platform. A handful of people did it (AOC, Omar, Taleib) but by far if you want a successful career you take a mainstream R or D position and just try to outdo everyone else in culture war takes. I'll point out that "the squad" is social democratic in nature, they aren't as far left as you can go by far.
A left position calls for redistribution of wealth and transfer of control of the means of production, which gets you attacked from nearly all establishment sides.
Obama turned out to be an establishment President (with bailouts, not prosecutions, for the architects of the housing bubble and crash) but he ran as an anti-establishment candidate.
Then, despite obviously being part of the establishment, Hillary tried to do the same, arguing that she as a woman she clearly wasn't part of the establishment ("Sen. Sanders is the only person who I think would characterize me, a woman running to be the first woman president, as exemplifying the establishment.")
She lost to Trump, who - despite being a billionaire white male - constantly attacked and was attacked by the establishment, in particular as a "populist", someone chosen by the people, not the establishment.
And until the DNC united behind Biden, Bernie was giving him a serious challenge, and Biden was relying on his anti-establishment rep with his "black firewall".
Meanwhile, Bloomberg was painted as the clueless establishment candidate and laughed out of the race.
A young politician (left or right) studying recent events would be smart to run away from the establishment, just as so many elder politicians have (while perhaps seeking establishment support in secret, and hoping not to be caught).
But facing enormous pressure from a younger generation that seems to be far to the left of Biden and was not happy with either Biden or Harris, but voted against Trump rather than for Biden.
And even with all Trump's failings as a person, it was a close election between the unpopular populist and the likeable establishment compromise. Is that evidence of establishment strength?
A left position calls for redistribution of wealth and transfer of control of the means of production, which gets you attacked from nearly all establishment sides.