So after having some looks at bitcoin mining and setting up nicehash on my pc (single gtx 970) to have a look at how it works (ofcourse I won't be able to make any profit because of power consumption), I wondered if buying an Antminer S9 and starting to mine at home with a powercost of 0,26$/KwH would be profitable or will I just lose my investment.
It'll be more profitable if you move to mining altcoins instead of bitcoins because of the current difficulty with bitcoin mining is very high compared to altcoins like ethereum, litecoin, bch, etc. Use a calculator for mining (you can search it on google) to see the estimwted amount that you could get with an Antminer.