You have to consider more than the upfront cost. These machines are incredibly expensive to run and consume a tremendous amount of energy. The long term environmental cost needs to be factored in as well.
No it's not. The LHC uses as much power as a small to medium sized city [0]. The next generation collider will obviously require a lot more energy.
What's your point anyways? We should only consider the cost and environmental impact of something if it's comparable to the most costly and impactful endeavors out there?
To first order, environmental impacts are roughly proportional to the amount of energy used, which is proportional to the amount of money spent. To first order.