You can loosely think of hydraulics like pulleys, whatever ratio of input to output power you create is accompanied by a reduction in distance moved.

So a weight of 1kg on an area of 1sqm could balance a weight of 10kg on an area of 10sqm, but moving the 1kg would only generate 1m of travel for every 10m of movement applied.

If you try and displace 1sqm by 10m, you are displacing 10 cubic metres. If you use that displacement to move an area 10x the size, it need only move 1/10 of the distance i.e. 1 metre

You need to keep adding weight (force) to achieve the movement. The initial weight will only balance the system.

I assume that the comic is about breaking apart the mountain, you don't have to move far at all to achieve destruction. You also need a watertight system.