If someone can earn x bitcoins mining and you sell it to them for less than x you are throwing money away.
All the other reasons you gave are also the exact reasons why it makes no sense to buy/rent the hashrate.
There is no way for it to work out for both parties. someone is going to be making a bad decision.
Suppose I have a rig that will mine 20 BTC over the next 12 months, and that it will burn 10 BTC worth of power doing so.
If I don't sell you anything, I make 10 BTC profit in the next year.
Instead, I can rent it to you for a year, for 9 BTC. You get 10 BTC back slowly over the next year, and end up with a 1 BTC net profit. I get the 9 BTC up front, and use it to buy another mining rig rather than having to wait for a year before buying it. I've effectively borrowed the 9 BTC from you at around 11% interest.
Aren't we both getting a good deal here? I'm getting money earlier than I otherwise would, and you're making a return on your investment.
Why not just be patient and get the whole 10? You are going to have to go through the work/hassle/expense of running the miner, why not get all of the benefit?
This is the one scenario where it makes a little sense, but I don't see it really happening because why pay that 11% when you are going to do all that work to generate the whole 10 anyway? If you need 9btc today you can borrow at a much lower rate, and probably spend less to generate/earn the 10 that you would running the miner?
The whole discussion is really moot because no one has miners that will roi at all, but the time-value of the coins is not that high.
