The problem with Bitfinex is that some people suspect that they use Tethers to manipulate Bitcoin's price, so even if you control your private keys, it still affects you, because it negatively impacts the price. The value of Bitcoin as store of value is being undermined by shady ecosystem. Hopefully Bitcoin today is more mature than when it was during the Gox fiasco.
Interesting theory and it is something I have heard of on multiple occasions before thanks to all the shady controversies surrounding Tether. Price manipulation will always exist no matter what if you ask me.
What we need to focus on is trying in whatever manner possible to lower the centralization aspect of the crypto ecosystem.