He never was a Democrat, or a Republican. He's a rich guy who loves attention, wants lots of media attention and adoration, and has no deep-seated ideas. He wants to smile, be rich, and have people like him. That's why he failed running for President and running for mayor of NYC -- people realize they could see right through him.
Establishment Democrats were going to do whatever it took to turf Andrew Yang.
Yang's politics align with AOC's politics. The Border Crisis will cause a massive hit for establishment Democrats in areas with high density of Hispanic/Latinos. That means Los Angeles. Could the GOP take Los Angeles? Probably not. But could AOC? That's a deeper and much more complicated question in terms of long term political strategy.
If AOC could plant a progressive loyalist in both LA and NY, she would effectively control Hollywood and a massive share of the entertainment industry. She could then leverage two of the biggest Blue strongholds in the entire country. Jeffrey Katzenberg's money printing machine for the Democratic Party would need to start paying fealty to The Squad and AOC. So with big establishment money and one of the most hyperactive growing platforms in all of politics, she now has a wedge to become a threat for POTUS.
All the enemies that the establishment Democrats made within their own Party have an incentive to align. The Progressive block does not have a major player with a military background. But Tulsi Gabbard has every reason in the world to want to hammer down on establishment Democrats. Bernie Sanders was gutted twice and cheated out of the ticket in 2016, he has reason to want revenge. Does anyone want to forget he got a thousand delegates in the last cycle who might prefer AOC? Elizabeth Warren was railroaded by her own Party. That ambush and hit job from Charlemagne da God was not some accident. That deep uncomfortable pause after he went for the kill shot wrecked any future she had.
Once Buttigieg realizes he'll never be asked to be VP, he'll start to figure out DOT was a place for him to take hits over Biden's oil and gas policies.
Yang's first crime is he can't be controlled by establishment Democrats. Yang's second crime is he's not a black lesbian Jew in a wheelchair with Tourettes unloading pure woke on everything in his/her/their path. Yang's third crime is he's Asian and frankly the level of acceptable racism in this country for Asian Americans is wholly repugnant.
Establishment Democrats created a two front war. The natural one with the GOP and then the idiotic self inflicted one with the Progressives.
Hunting down Yang was more about neutralizing where AOC can be strong and influential.
Here's the larger problem, Jon Ossoff is a stone cold unhinged Progressive. He might not platform as such but he has more alignment with AOC than he does with the establishment core in the Party. DNC HQ had no choice but to back him by shipping containers full of cash to win the Senate from the GOP in 2020. But make no mistake, the problem is going to be the next five Jon Ossoff types that the Party has no choice to support in small level races. The Progressives have laid deep roots in Big Education and that forms a feeder system for them.
AOC, even without Yang, has an exponentially growing number of future loyalists being loaded in the chamber and ready to fire.
The establishment Democrats can stop Andrew Yang in New York right now, but can they stop the next 20 like him all up and down the ticket?
People are looking at Yang's loss without looking at what Yang represents - Progressive upstarts can force their way into the daily media cycle and there's nothing the establishment Democrats can do about it. Once you can get your platform in the public eye on a consistent basis, you've legitimized your ability to hold a "second front" in a long term political war.