Bitcoin is consuming power to secure the integrity of the blockchain, that is the reason. It is not "no reason". If you could suggest another permissionless consensus mechanism, then Bitcoiners are open ears, it has been discussed many times at bitcoin-dev.
Bitcoin survived an attack from its own wealthy proponents, miners tried to increase the blocksize for speed, which resulted in the fork Bitcoin Cash. Possibly the number of validators will always outnumber miners.
And the code base is not stale.