Ann: Quarterly Activities Report, page-128

ARV would need to make additional investments to plan the mine and engage contractors to dig out ore and transport it to RH. I suspect additional investment would also be required at RH and they would also need to recruit people to operate the plant as well as admin staff.

I suspect they looked at the costs and decided they needed to run RH for a certain number of years to just pay back the startup and running costs before they can make a profit.

Just think about it. If your startup and opex are higher than your profit you end up with a loss which makes things even worse. They will need some time running at a profit to pay for starting the process and I guess 3 years is the magic number based on initial estimates.