If one thing mining has thought me, is to never to buy a fully assembled GPU mining rig from anyone in some cases not even friends. Trust me at least you get to keep the friendship. And you will be better off knowing what kind of friends you have then losing money to them even after you know what kind of friends they are.
Everyday I see people asking, how much can I make a month if I bought a rig of 6 GPU GTX 1070 from you. If you are one of them, you should not get involved in mining at all. If you want a guaranteed profit you should have just left your money in the bank. There is no such thing as a free lunch.
Lesson 1.
It all goes back to basic common sense. Why would someone sell you something that would make them more money ? You got to be pretty stupid to think that someone would actually sell away their golden goose that lays them golden eggs, but not selling the eggs itself. Unless of course there is something really wrong with the goose lol.
Lesson 2.
Mining is very easy to setup if you have a thing for computers. If you don't then you shouldn't get involved in mining. You would be better of buying the crypto currency of your choice straight from the exchange itself.
Lesson 3.
Never buy a used mining rig or a used ASIC miner. Buying any of these is like buying a 2nd hand car which has 500,000 km on its mileage. Even a car doesn't run for 24 hours a day for 365 days.
Lesson 4
Know what your doing and buying. I go on facebook,lazada etc, and I see ads of people selling x6 GPU GTX 1050,1060 rigs for USD 3,000 or more. That's the exact price it was 3-4 years ago, and some of them are not even brand new. There will come a time which is soon, when running those will no longer be profitable anymore and that your electricity cost will be more then your profits alone not to mention your initial investment cost.
At the end of the day nobody is gonna be there or feel sorry for you if you mining hardware does not gain back your initial investment through mining, and the person (probably a miner themselves) who sold you all those outdated mining hardwares had every intention to rip you off. They will just camouflage the rip off with a word called "business". Like they say it's nothing personal, it's just business.
Most miners are scumbags and douche bags whose morale compass are all screwed up beyond recognization. They will even go to the extend of stealing electricity to run their rigs, because they think it is okay. For them stealing a candy bar from walmart is a big no no and they will turn their nose up, but them stealing electricity is completely fine. That's how the miners are these days.
So the next time you gonna buy a rig from a miner or a friend just think twice. They all have the same characteristic. They will look all nice telling you how much money you can make through mining and try to teach you about it, just enough to get you involved into the mining scene so that they can unload all their old hardwares onto you.