Any software engineer can clone Twitter. The value of it is in the network and the high cost of users switching because they can't convince the people they follow and those who follow them to switch at once. The same applies to Bitcoin, but miners have an even higher cost of switching because they have specialized hardware that can only generate revenue on the Bitcoin network. Ethereum validators have a much lower cost to switch.
> proof-of-waste
It's Proof of Work. Productive work has value and in this case, it's widely distributed censorship-resistant validation of transactions.