1BTC per day is too high i don't think there is legal methods to earn such amounts in legal ways, you can make good profit if you sell your goods and services , and if you have very good and needed goods or services you could make 1 BTC in short period
the only way is via mining, 100-150 tera should suffice for 1 btc day, minus the cost, but if you have very electrcity it should not matter much, the real problem is the initial investment
Heck, if there are mining equipment capable of producing 100 TH/s a piece, it would be too high of a price. Also, I think most modern miners are still kept on the manufacturer's data center to hash for them before they sell it, right?