50x 1080Ti's huh.
And when do you intend to make money?
You are ready to dish out 40 grand worth of cash and you don't even know what you're going to mine? Seriously?
Ballers gonna ball.
My advice would be to get one rig first and see how it goes for a month or so and then make a decision. It's going to take a while till you going to figure everything out.