Mining is no longer a hobbyist pastime. It has become a professional endeavor. If you want to make money mining, you need to research and understand the following:
1. How mining works.
2. How difficulty works.
3. How mining pools work.
4. How to evaluate mining equipment and how to buy it.
5. How to evaluate equipment manufacturers, their reliability and their lead times.
6. Future difficulty and how to predict it.
7. The financial aspects of mining, especially the effect of the difficulty.
8. The history of mining.
9. Mining alt-coins.
10. Alternatives to buying mining equipment.
People that jump into mining without taking the time to become experts simply lose money. There has been, and there continues to be, an astonishing number of people that have lost money on mining.
TL;DR: The secret to mining profitably is to pay less for the equipment (and power) than it mines. Determining how much it will mine is not as easy as you think. This is not a really a secret, but somehow most people just don't get it.
Wow, thanks for the explanation. I guess most people in forum is right about not mining is a better decision....