What are the lessons to be learnt from the collapse of socialism in right before the end of the 20th century?

the issue with forming a mass movement is it getting infected with idpol

This is a problem, but this is also why it is important for our social emphasis to be on UNIVERSALISM as opposed to the PARTICULARISM of ID pol. Take for example, the Civil Rights Movement: it was a movement that sought to address the social concerns of black people, however it did so in a universalistic way that recognized that we are all human. Now days, if someone was to say "we are human", they might be "called out" for "microaggressions". But it is this universalism that has underpinned all successful revolutionary movements, and it is necessary that we recover it.

this tbh

even tankies don't believe the ussr was socialist at that point

I'm not even on the left, but this holds true for any movement. I think it was true when the so-called alt-right was in its infancy. What is necessary is something like a prime directive. Once known, the subject can act in a way representative of the whole. This is what would be required of humanity in intergalactic space travel. Consensus and reporting back takes too long to be efficient

Don't you think the real danger to socialism would be how insanely materialistic people are and how badly they crave non-essential things? Greed wins out and people are swayed by their feelings, not arguments (most of the time)

I don't see why we can't have a mass movement based purely around class issues today and convince workers to be smashies part of the time and crowbar those who would bring idpol cancer.

We have 60 years of harvest left at current rates of soil depletion. Nuclear weapons are proliferating. As we approach full automation, it will lead to starvation instead of prosperity. Billions of people will be forced to migrate due to rising sea levels, thus triggering the rise of even greater reactions to the "left". Droughts will last decades and floods will be worse than ever.

This is humanity's darkest moment, and the greatest opportunity of the real Left to make a full resurgence and bring about freedom, equality, and solidarity. We cannot let idpol liberals posit themselves as the left and yammer on about race and gender. I fucking hate liberals. They need to be beaten with metal rods if it means saving humanity.

It was socialist but after Stalins death state machine was infected by careerists and opportunists. Actually, Stalin and his repressions were a cause of so the state held only on his authority

...

The meme's not wrong in the sense of violence, but I'll never give up on workers' self-management and undiluted council democracy. The ends justify the means, so long as what the means create do not clash with the end vision.

People should really stop conflating Lenin’s ideas with Stalin’s ideas. They were very different people with very different views, no matter how much Stalin liked to pretend otherwise. Lenin was certainly no fool, and very much aware that the failure of all European revolutions left Russia in an awkward position where realizing socialism would be near impossible. To him, it was primarily a matter of holding down the fort whilst awaiting further revolutions and uplifting Russia out of medieval primitiveness.
Lenin envisioned a long period of essentially capitalist development in Russia, where the peasantry would be slowly lifted up out of feudalism through an extended NEP whilst society was to be reorganized into a collection of cooperatives as a means of inducing cooperation under capitalist conditions. This would be accomplished by a sort of "cultural revolution" where the backwards, reactionary culture of Russia would be eradicated and replaced by a more enlightened culture based on socialist principles which should prepare it for a future transition out of capitalism.
Indeed, Lenin even advocated against promising socialism to the peasantry as he believed it would give them false expectations which the party had no ability to actually fulfill under the present material conditions. All that could be done was to slowly uplift them materially and culturally and leave all business of further development to the future, and the ideals to be spread through a sort of natural osmosis between the various soviets.
To Lenin, unlike Stalin, this was really all they could hope to achieve without reinforcements from either Western nations which could lead the way for Russia, or from Eastern nations which could take Russia’s struggle against the West as an inspiring example and join them on the road out of feudal poverty into a higher stage of development. Indeed, in one of Lenin’s last writings on the subject before his death he sounds more like Dr. Wolff than Stalin, as he argued that this capitalist system of development through well-educated workers’ cooperatives was the system through which Russia would head towards genuine socialist development.

Vanguard is shit. Central planning is shit.