# <center><i class="fa fa-edit"></i> 2.5 Putting It All Together </center>
###### tags: `Blockchain`
The following notes are taken from [Coursera](https://www.coursera.org/learn/cryptocurrency/home/week/2)

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### Mining Economics

    if mining reward     > hardware + electricity cost -> profit
(block reward + tx fees)

### Bitcoin is Bootstrapped


### Complications
- Fixed vs variable costs
- Reward depends on global hash rate
- Exchange rate of Bitcoin

### 51% Attacker
- Steal coins from existing addresses? ❌
- Cryptographic problem, can't steal on node level
- Supprection some transactions? ✅
- From the blockchain
- Controls consensus, prevent creation of blocks
- From the P2P network ❌
- P2P Independent of consensus
- Change the block reward? ❌
- Can't control copies of Bitcoin software honest nodes are running
- Destroy condience in Bitcoin? ✅
- Likely, lose trust in decentralization