1. ROI isn't that much of an issue for me, my goal is to generate a stable-ish (I understand the rates can go up or down, most of the times down
) income so I can live off that. I get bonus points for being in Romania and life being very cheap compared to other countries.
It's completely up to you wether you decide to start mining or not... But in my personal opinion, ROI is always important...
An S9 delivered to your door will probably set you back ~$3000... so with your $10.000 budget, you can buy 3 S9's... They'll make about $1000 in the first month, but since the diff is expected to go up 14% next time, you'll probably only make $860 your next month... Maybe $760 in 2 months,...
The odds are very big you'll need to keep on mining more than 15 months in order to recuperate your investment (just an eductated guess tough... I can be wrong)... Only then can you start making a profit!
https://bitcoinwisdom.com/bitcoin/difficulty3. Exactly how noisy? Is using a cheap-ish isolation a solution or is it money flushed down the toilet? Same question about the heat issue. How big of an issue? Is it solvable by drilling 1-2 holes in my wardrobe and setting up 2-3 fans inside it? Or do I need voodoo stuff like a freon / water cooling system?
Like i said... 1 S9 seems to produce about the noise of a loud alarm clock when 4 feet away... About the heat: 3 S9's produce ~4000Watt of heat... I don't think 1-2 holes will be sufficient
300$ profit / unit in a month for me is good for me, life is cheap here. Sure, ROI might take a lot but it's all fine for me as long as the income flows.
As long as you recuperated your investment before the monthly income turns negative (this can happen!!!)
On the warranty issue.. are these things known to break down early / often? Are they easy to fix? Do they need special maintenance or down time from time to time?
https://cse.google.com/cse?cx=016660200577587308545%3Aesf40ml9aag&ie=UTF-8&q=bitmain+s9+warranty&sa=Google+search#gsc.tab=0&gsc.q=bitmain%20s9%20warranty&gsc.page=1Read this first
I will also look into altcoin.
I unplugged my miners years ago, but if i was in your situation, and determined to start mining... Altcoins would be my first choice (i do pay +27cent/kwu at the moment)