If Banks are going to use quantum computers or any Computer to fight a war against Bitcoin they would need a better approach than price manipulation.

Before I dove into bitcoin in 2013 I apply the practice "If you can't beat them join them until you can beat them".

The formula for banks to gain control of bitcoin is not a very hard one. They just need to buy it all. If they accomplish this we the people will have failed as the banks will have Gold, Oil, and now bitcoin.

Another way is for them to actually decrypt the Bitcoin Blockchain.