At roughly $850 per card, a $50,000 investment in GPU rigs would equate to roughly 50x1080 Ti's, including all other components and hardware to run the farm (rough estimate).
1st ... There is a word wide GPU shortage ... I dont think you can buy 1080Ti cards for 850$/cards ... those cards are way over a 1000$ without taxes ... and the limit is one-two card/customer right now , its not going to be easy to get that 50 cards
... as of today February 1 - 20182nd ... you still need racks , pdu's , surge protectors , network switches , wiring , cooling equimpent , framing , if you want to build a rigs with customer grade psu , those psus price are crazy high also , those psus price doubled in the past few months ... 400-1000$...
3rd ... If you building your business from someone else money, and risk your family future, based on what whattomine.com telling you , you are a idiot ( sorry ) , you going to be one of those members on the forum who is coming back and asking questions like : " WHY MY EARNING IS LESS THAN ALL THOSE ONLINE CALCULATORS TOLD ME ", none of those calculators dealing with difficulty increase ... there is a great reading for you HERE
4th ... If its not your money , go for it
I don't think a 50k investment justifies a move of your family or changing your day job, 50k is like 25 antminers if infrastructure is free, or say, 15-20 GPU rigs depending on the cards involved.
You can not get 25x S9 from $50k - as of today February 1 - 2018
Last time Bitmain was selling Antminers it was $2320 / S9 , you still need a psu , and pay for shipping ...
Shipping to USA from China for 20 x APV3++ psu with fedex is around 500-600$ + custom fees if you get any
Shipping to USA from China for 20 x S9 Antminer with fedex is around 1100-1200$ + custom fees if you get any
And you have to make sure you have 35KW available
and you can deal with the heat and noise So ... 20 x S9 going to cost you $2320x20=46400$ + 1200$ shipping + Psu $105x20=2100$ + shipping 600 Subtotal: 50300$
20x S9 13.5TH/s going to give you around 270TH/s...