Bitcoin Forum

Someone has been selling 2 GH/s CEX.IO vouchers on eBay for a couple of dollars each. Apparently these don't ever expire meaning that they continue hashing and hashing and hashing forever.

Now, my question is, why is this not a good deal? Isn't the potential reward infinite? Wouldn't it make great sense to spend a finite amount of money to get something that gives an infinite amount of money back?

The profit will slowly turn to zero, and cex.io might discontinue it. Also the price of ghs can fluctuate, and eventually they will be worth less than what they are worth now, so when you want to cash back into btc, you are left with nothing

Before you jump in, consider these:

1. You may earn an infinite amount of BTC, but it will take an infinite amount of time to do so.
2. Right now, 1 GH/s at cex.io earns about $0.008 per day (less than a penny). How much are you willing to pay for that?
3. The amount you earn will get smaller and smaller, halving every 4 months or so.

until you redeem voucher those GH/s will mine for cex.io. Second point, check Ghs price chart (last month) ... dropped drastically, and this will continue due to raising difficulty. In few months 2 Ghs will be worthless.
 

 

If these numbers are correct:

I have been made aware that these numbers are indeed false

#1 for each GH/s you earn $0.08 in BTC each day 0.008$ is more likely
#2 the earning from #1 decreases by ~1.25% each day (~halfes every 40 days)
#3 for each GH/s you pay 2$

you will ROI after 33 days and double your investment after ~118 days. After ~304 days your return will be 2.55 $, after 340 days 2.56$, after 458 days 2.57 $ etc.

https://i.imgur.com/k7FTpkf.png

Keep in mind that the price for BTC changes as well as the rate the difficulty changes.

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Did some research on ebay to see how the prices are. If you take 2TH/s (2000 GH/s) you pay 3.0475$ [1] per GH/s and end up with this (ROI after 63 days, 1.50 $ profit after 298)

https://i.imgur.com/DdoD5FP.png

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If you buy a single GH/s 4.45$ seems to be the best price [2] unless you have luck while bidding.
ROI: ~207 days
.10 $ after ~ 304 days

https://i.imgur.com/W61j4ka.png


[1] http://www.ebay.com/itm/2-TH-s-or-2000-GH-s-CEX-io-cloud-Bitcoin-mining-voucher-contract-LIFETIME-/201143869065?pt=US_Virtual_Currency&hash=item2ed51bde89
[2] http://www.ebay.com/itm/1-GH-s-CEX-io-lifetime-contract-voucher-ASIC-BitFury-BitCoin-cloud-mining-CEX-/181490588686?pt=US_Virtual_Currency&hash=item2a41ae9c0e

You might get your money back, but "non expiry" contracts are just a marketing gimmick. The voucher will become worthless over time anyways.

You would be mining dust after awhile anyways. {Increased Difficulty will eat it up}

Yes it will hash for you forever. However, they charge a maintenance fee which you would need to pay from your shares submitted. When the payouts turns to 0, you would have negative balance and you have to pay for them. Even though it will mine for you forever, it isn't free.

The TL;DR version is that the mining rewards will eventually approach 0 as the difficulty increases. Since CEX charges a fee for electric and maintenance your actual rewards will actually reach 0 at one point. 

1. Cex.io is just a company and it won't be in business forever.
2. As difficulty goes up, mining reward goes down.
3. Block reward halves every ~4 years, and there will be only tx fees for block finders in the end.