>From what I understand, a Bitcoin inherently has value due to the electricity and other costs required to mine a Bitcoin into existence
Actually, the cost of mining is more closely tied to the security model.
Proof of Work (Mining) is the means by which consensus on the state of the blockchain is reached. Effectively, the chain which is the longest (most blocks mined) is picked up by the network as being correct.
So, in order to alter the history of the chain 100 blocks back, I would need to go back and start mining from that block forward, one block at a time, until my blockchain with the fraud in it is longer than the main block chain, which would still be progressing forward.
This is where the hashing comes in, because I can't take shortcuts to get to parity with the main chain, as each successive block hash is a product of the previous hash, which I can only get by brute force guessing.
So in order for me to overtake the main chain with my fake blockchain and have the rest of the chain accept it, it should be clear that I would need to own at LEAST 51% of the network hashing power, as otherwise the main chain would just keep pulling away from me, and my chain would never be longer than the main one.
However, thanks to the cost of electricity and infrastructure to own 51% of the network hashrate, it is incredibly unlikely that anyone would have the resources to carry out this attack... and here's the really awesome game-theorish part...
Even if someone did have that much hashing power, the rigs they would need to buy are incredibly specialised for one thing only. Bitcoin mining. So in attacking the network for some small doublespend gain, I would have completely destroyed the value of the network by invalidating its security model, which would lead to a massive crash in bitcoin, leaving the millions (billions?) of dollars I have invested in the mining equipment as a total writing off.
... cont