i think Bitcoin is only profitable if done at large scales. you must get expensive mining equipment and of course it consumes a lot of electricity monthly. Also its usually much more cost effective to buy Bitcoins with this money instead of using it to buy mining equipment.
As based on what you pointed out it is easy to conclude that it is much better to buy bitcoin instead of mining it specially now that the graphic cards for mining bitcoin increases tremendously though with a proper miner will guarantee you to earn passively its cost defeats its purpose plus the risks of volatility may affect your estimated date of your return of investment.