Okay, I get your first point. But, first of all I already have a company and second the electricity costs are not scam. I get the electricity costs from the company of my father, who only pays 0.05 kWh EUR (thanks to good contracts with the energy provider, since his company uses a lot of energy per year). Regarding the taxes: the Htax factor in my county is 300%, meaning that if I make 38k Eur in profit I have to pay 7765€ Einkommensteuer (personal income tax) + 1417€ Gewerbesteuer (commercial tax), which makes 9182€ in total taxes paid after one year and would still leaves a profit of about 20-30k EUR IF Diff goes back to 30k and the BTC price only increases to 50k. Last part confirms your first statement of ROI = 3 years.
With such taxes, you will very much lose to miners from other countries.
In russia, miners can legalize and pay from 4 to 13% of the money they receive from the cryptocurrency exchange. But many miners exchange cryptocurrency for fiat and pay nothing.
There are also small taxes in Kazakhstan, but a 25% mining tax is a lot and unprofitable.