It would require that person to acquire so much hardware that it literally would take years to perform this attack.
Not really, if that "person" or organization have enough money and influence it won't take much to perform it.
existing farms have enough extra capacity to increase their hashrate to a point where the attacker would need +60 or even +70% of the hashrate.
No.As far as I can tell, farms can expand their capacity to compete with attacker and not let him get 51% but they can't make him need 60-70% of the hashrate to perform it.
It would be an utter waste of time and money.
If the attack succeed, it won't be a waste of money.
Just like how they banned drugs? That definitely worked. It made the prices of drugs sky rocket and the industry be worth like $400 billion annually.
You can't compare drugs to
BTC.If they ban it, price will 100% collapse not sky rocket.