They are "sharing" their products with us for the cheap because they will make large amounts of money from the initial sales. People will then realize that a single jalapeno sounded great when the difficulty was 1.7M, but oh no, I need more hashing power now that the network is over 200Thash. Hell they are only $150, let's get a couple more!
Before we know it, the ROI time will be years and no one will be earning well. On the brightside, bitcoin as a currency will be very secure.
How is it more secure? Going to take the less money to buy 50%+ as it always has in your 200Thash scenario. 6 million. (30k for 1TH box)
Current speed of 13THash using $600-1,000 a gh is 7.8 million to 13 million. (best FPGA to new GPUs)
Total bitcoin market cap is: 67.13 million http://blockchain.info/stats
Agreed. The determinant of bitcoin security is its market cap. The more bitcoins are worth the more profitable it will be to mine (all else being equal), and the more money will be put into mining. Thus, a new miner entering the market would have to pay more to get 51% of the total hash rate.