People like positive change - better standard of living, cheaper and high quality goods & services. They get the opposite and they don't like that, there's no mystery here.
> the original sin of capitalism is change over time
It was never supposed to be negative change, and calling what we have now "capitalism" is quite a stretch, the meaning of that word is now so vague as to render it meaningless.
> The thing is right now we don't have a completely clear picture of what the future is.
The future is what we make it and we have a pretty clear picture what actions lead to what consequences, it ain't exactly simple for everyone to understand but that's not necessary either. The problem is, the media and politicians only muddy the waters instead of elevating the valuable insights and proposals.
> the walls of the environment are closing
Poetic but misleading. The environment is a systemic function of multiple factors, it's really unhelpful to make it a political issue for the purpose of peddling more sacrifice from those on the losing side of wealth inequality.