Capitalism requires growth. Resources are finite. A crash is inevitable.
Previously there were new places to conquer and resources to exploit.
Now the game has changed, there are no new frontiers.
Our modern capitalism is in reality no different to the old slash and burn of primitive agriculture. Find a resource, exploit it and move to the next. Today the additional complications are pressure of population which means that exploitation is on a vast scale. In the past the associated small scale environmental degradation could be tolerated, but today such degradation is on too vast a scale, and impacts too many people, to continue unchallenged. The real elephant in the room is of course the scale of modern capitalism, and that is because there are simply too many of us.
Like it or not, we are simply lemmings running headlong towards the cliff that we know is in front of us. The population overshoot will be distinctly untidy. There is no point in discussing capitalism and it's place in the modern world without considering the population density that dictates it's scale.