1. If I buy S9 With $1520 , I will be able to sell it in future for $1520?
2. How much i will earn with it per day?
3. I will earn life time or just few years?
Thanks
1. u cant buy it for 1520 usd, u will have to pay for 12.500 GHS right now 12.500x0.00011700= 1.46 BTC aprox, yes you could sell it at market at the price it will be when u want to sell (probably more in few month from now, and in a year probably less then what u pay for it), depens of the price of BTc, if there will be restock, and depending of the increase in difficulty
2. aprox 5%-7% per month, and it is decreasing each month for 0.3-0.6% aprox
4. probabyl it will be S10 or S11 in 2 years from now, so not for life
You should keep in mind that if Hashnest restocks S9 miners, the approximate price will be about $1350-$1400 per item. It is 1.09 - 1.13 BTC. At the market current price is 1.46 BTC per 12.5 TH/s. So it will be an immediate drop in price by 22-25% that will neglect about 3 months of mining. And I would say that there is a high chance that S9 miners will be restocked in 3 months... Needless to say that in July the price of one S9 miner will likely drop even more: to $1250 - $1300 (with PSU).
It may be more profitable just to lend your BTC on Poloniex and wait for restock.