Where is the trick?

[Anynomous]

This topic was also discussed here:

Miners profitability

Quoting my own post from: The ROI would be 91 days. This is equivalent of an income of 600/91 = 6.6$ or around 19 Grin per day. The question is if the G1 Minin is available though, their website that the first batch has sold out, you have to contact the sales from iPollo: https://www.ipollo.com/ipollo_en/interhashMikecrm.html

The ROI for the G1 miner is approximately 109 days, assuming there are not enough miners to increase the hash/graph rate:
https://www.coincalculators.io/coin/grin_32?Hashrate=42&HashFactor=h&Watt=2800&ElectricityPrice=0.1&PoolFee=1&HardwareCost=25000&LH=&Difficulty=24

I think you should asume there are enough miners to increase the hash rate. Also it is very hard to get a G1 miner. You can also buy the G1 mini miner which has a graph rate of 1.4. The economics are the same for G1 and G1 mini, the price per graph rate is approximately the same, also the power consumption per chip is the same.