NiceHash shows a profitability of $9/day (1) given $0.08/kwh which is average in China (2). So to get a positive return on your investment assuming a cost of $700 per card, it takes less than 80 days. Never before have you been able to launder and invest your money at the same time.

The questions of number of cards and electricity usage are pretty secondary and easy enough to hide. Go off grid, setup a similar legitimate company, lots of options to hide it.

This is backed by the fact the vast majority of hash power for BTC comes from China (3). There are world wide shortages for sha asics and gpus. I'm not describing a hypothetical.

(1) https://www.nicehash.com/profitability-calculator/nvidia-rtx...

(2) https://www.globalpetrolprices.com/China/electricity_prices/

(3) https://www.statista.com/statistics/731416/market-share-of-m...