I've seen this balloon to hundreds of consultants. It can break a company. You get huge sunk cost into you're continually 90% done ERP and management either doubles down to spend one year to just get it barely working and stop, or cancel it.

In my experience companies end up paying as much money as they can.

The companies themselves are to blame, too: they absolutely refuse to change their processes, so the software must adapt to them, no matter what the cost.