Based off a cost of production of $364 USD per tonne of...

Based off a cost of production of $364 USD per tonne of concentrate and revenue of $750 per tonne, the company was forecasting EBITDA of $75 million per annum - volume of around 200,000 tonnes per annum
So, even if prices are falling to $2000 USD per tonne, the company will be generating multiples of its earlier annual EBITDA forecasts
As for investment banks, they have a history of putting out headline seeking predictions of massive moves in particular asset prices ( currencies, commodities, interest rates )
- if/when they get the direction of the move right, they subsequently update the forecasts with more modest targets. In the meantime, their trading desks and key clients have already adjusted their portfolios - of course before the media outlets pick up the big predictions