I feel that this socialist mentality that their ideology is inevitable as is demonstrated in your post only hurts their cause. What benefit is there to saying "We are going to win in the end for sure."? That just makes supporters of your cause more likely to gravitate towards apathy, which is also demonstrated in your post. I feel like neo-fascist propaganda is much better in this respect, they do not represent their ideology as inevitable, instead they represent it as the underdog fighting well above its weight. This gives its supporters a feeling that they need to give it everything they have, as the fight is impossible to win otherwise.
Pic related, neo-fascist propaganda. Notice how it symbolizes the movement as a mere plant, a hope if you will. This is to spur them into action while making sure not to demoralize them in the process. Seems like a better strategy if you ask me. If you truly want people to take action then i would look into optics.
Escaping fauxialism/radlib bullshit
Aaron Barnes
Robert Flores
Philosophy Tube its a leftist youtuber, probably the most famous and with the highest production quality, but also talks about gender and the like (he himself is bi and made a video about it). Dont know if he would be your taste.
Chapo Trap House, like the other user mention, its a trash tier leftist community, good for memes and the occasional news, with a bit of casual discussion. Dont expect enlightened people, take it as the leftist equivalent of a more polite and less trashy Yas Forums.
But I think their heart is in the right place.