At the beginning it was just a idea but... it works, we (a friend and me) did it now for twotimes).
First up: you need a few money for a short time, we took a credit for 4 weeks (nearly no fees because of the short periode)
Step 1:
Order 10 Bitminer S9 from a Wholesaler for a lower price (we payed about 1900$ per unit).
Step 2: When u have the Miners start an auction on ebay for 9 of them for 10 days. Try to get the 1900$ per unit back, it should be work 😉 ( we sold them for round about 2100$ per unit)
Step 3: Let the 10 Miners run for 10-12 days (generate Bitcoins)
Step 4: sending the 9 Miners to the Ebay-buyers
Step 5: get your one for free, pay back the credit and/or do it again. 😉
Do it by your own if you like.... start calculating...