Mining contracts give you the illusion of "passive" income, but its really just an illusion...sort of. The issue is the difficulty increase. You need to find a calculator that takes that into account.
mycryptobuddy.com/EthereumMiningCalculator
If we use the "dynamic graph" it will take the projected difficulty increase into consideration in your forecast.
mycryptobuddy.com/EthereumMiningCalculator
So, it costs $14,000 for 500MH for Ether mining (Ether mining is considered the most profitable) for 2 years.
In a 2 year time span, we can project with the rate of difficulty increase, that you will mine a total of 47 ethers. "Profits at this difficulty" is deceiving because it doesnt take into account the difficulty increase. You must look at the chart.
We can only assume that the price of an ether stays the same; we have no idea how much it will cost later.
47 x $350 = $16,250. That's barely a 20% ROI! In a 2 YEAR timespan.
You are essentially gambling on several factors:
1) That the price of Ether and the Ether token itself will still be relevant, and/or more relevant and thuis higher in price
2) That the mining company is still going to be around in 2 years. Or even 1 year in Hashflare's case
See, once again mining is deceptive. Mining is really only profitable for the average joe if you find a coin that suddenly jumps up in value with a low mining and difficulty. You might as well pound sand. And its especially deceptive because for the first few months of your mining contract you are going to see good revenue, but as the months go on it will decrease. For those who are not particularly savvy with finances, they might think they are making bank, but in reality they are barely making anything extra.
Unless you have a $50,0000+ investment fund ,mining just isn't worth it.