Thanks for sharing your thoughts on this intersting topic. But I think your decision to decide for monthly payout and exchange to € for the current exchange rate in scenario b, is what makes the scenarios not comparable. I think you should compare the total amount of BTC you own after one year. If you would take your initial BTC from scenario a and partially (e.g., every month) cash out earlier (what would be comparable with your scenario b) you would also have less then 6778€. If you compare the total amount of BTC you have after one year, your table of scenario b shows that you would own 2.01 BTC. Compared to scenario a this results in 2.01 - 1.97628 = 0.03372 (1.7%) additional BTC in your pocket. Now you are free to do with your 2.01 BTC what you want. Done this way, this shows that mining is slightly more profitable than buying and holding. This higher profitability comes with higher risk. That means while holding your inital BTC you are free to sell it any time, while investing in mining (following my adaption of scenario b) lets you access your BTC after one year.