Why is that proof of work of any value, to anyone?
Hard work, just for the sake of hard work, is a great ideal to the the previous generations - but we traditionally have based our economy on how much your work benefits someone, not how hard you worked.
Mining bitcoin is extremely hard, with precisely zero benefit. The only thing of value is the work itself. Quite zen, even.
You’re making it sound like you genuinely don’t understand proof of work. Proof of work is the reason that it is effectively impossible to fraudulently alter Bitcoin transactions. Again, it’s fine if you don’t care about that because you don’t see any value in those transactions, but surely you recognize the huge importance of preventing the modification of previous transactions in any sort of payment system.
It isn't proof: you could have used a digger. The point of Bitcoin-style proof-of-work is that everyone has to use a teaspoon, and if you want to 'go back in time' and rewrite transactions you have to do more work with a teaspoon than everyone else is doing.