You could just as easily argue that "things will be more or less fine" is highly evidence based (things have been fine in the past) and in contrast millenariani

You could just as easily argue that "things will be more or less fine" is highly evidence based (things have been fine in the past) and in contrast millenarianism has an awfully bad evidentiary track record. A mass extinction event is underway, but it's not just starting. We are not at the beginning. There is this idea that the premodern world was "basically natural", but the reality is that 70% of animals larger than 45kg that were present in North America when humans arrived are already extinct. There is no Eden to go back to or preserve. The world hasn't been in equilibrium since hominid intelligence started taking off and our only constant is change.