By ruining the reputation of bitcoin/crypto in general, the average person would likely never touch it.
that's where you are wrong.
when some shitcoin is created or some ICO scams people, the world in general is not going to say bitcoin is bad! bitcoin had nothing to do with it. if anything people are going to stay away from ICOs and shitcoins and in general it will ruin the reputation of altcoins. but nobody cares about that because altcoin reputation is already in ruins.
while you are right on that aspect, I'm more referring to the general market, if banksters control the price, they can potentially just make it be so unsteady that noone would use it?