[tobiaswk]

Great points. The thing is though that a double spend would harm both the attacker and all others on the network. It would weaken the trust. It is a double edged sword. You would have to do the double spend without anyone noticing and then liquidate your earnings as fast as possible. With more combined hashing power this would become very hard to do.

There are a lot of problems other than double spend with the Bitcoin. Transactions fees rise very quickly because of the block size limit of about 1MB. You can't really rely on 0-confirmation transactions. The saviour lightning network in my opinion is the wrong solution to the scaling problem. It changes fundamentally how bitcoins are exchanged and steers away from the original white paper by Satoshi. Not that this is wrong... it just becomes another project altogether.