https://academy.binance.com/security/what-is-a-51-percent-at...
https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_...
https://bitcoin.stackexchange.com/questions/658/what-can-an-...
"An attacker that controls more than 50% of the network's computing power can, for the time that he is in control, exclude and modify the ordering of transactions. This allows him to:
* Reverse transactions that he sends while he's in control Prevent some or all transactions from gaining any confirmations
* Prevent some or all other generators from getting any generations
The attacker can't:
* Reverse other people's transactions
* Prevent transactions from being sent at all (they'll show as 0/unconfirmed)
* Change the number of coins generated per block
* Create coins out of thin air
* Send coins that never belonged to him"
Doing a reorg of the blockchain can cause all sorts of problems, and reverse all sorts of things, depending on what those transactions were, and how they are re-ordered.
This is a vague notion that doesn't make any sense. The purpose of the design of Bitcoin was not to give equal representation to every CPU. It is to prevent undue interference in transactions by third parties. And by that measure Bitcoin is definitely decentralized enough.
To do anything nefarious you need at least 51% of hash power and to not care that you are damaging the integrity of the blockchain, and even then you can't steal from or rewrite the blockchain - you can only prevent future transactions from going through.