> If I had >50% hashing power of BTC(for exactly 1 transaction), I can make the current chain say anything I want, like give me all the BTC, and it would become

> If I had >50% hashing power of BTC(for exactly 1 transaction), I can make the current chain say anything I want, like give me all the BTC, and it would become valid and "permanent". No, this is a big misunderstanding of how it works. Having more than 50% doesn't give you superpowers, it just means that you're able to create VALID blocks faster than the rest of the network combined (creating invalid blocks is useless), which allows you to censor transactions (by not including them in your blocks, which will be the chain with more work because you have 50%+) and you can TRY to do double-spends. A double-spend gets exponentially harder and more expensive to pull off the longer your target waits before considering the original transaction final, because you'll have to rebuild all the blocks generated since that transaction was included in the chain, so that your parallel chain that doesn't include that transaction becomes the chain with the most work that everyone follows.