You didn't name the exchange you're using, not all people have access or are registered to a fiat exchange with enough liquidity allowing to sell large bags at a good price. And in the other way it's even harder not many exchanges will accept large fiat deposits above $50k or 100k in one time without requiring long extra KYC if they accept them at all. In addition I assume if something is wrong with the recipient bank an OTC service will be far more reactive to resolve the issue and give documents than a customer support from a random exchange.
Sorry I have been gone.
Not naming the exchange is simply a PRIVACY THING on my end. I am sure you understand that!
I have never needed to trade at $50K or above at any one time so far. No issues ever with a wire transfer to my bank directly from the exchange. Again, as mentioned above the entire process takes 2-3 hours until the funds are 100% liquid and good to go! I don't think liquidity is a factor here. Picture the process. I move some hardware wallet BTC to my BTC receive address at the exchange. In around 10-15 minutes I get a chunk of confirmations on the transfer so the exchange is satisfied its a done deal. Then I willing pay the 1% (maybe 1.5%) conversion fee to turn the BTC held there into the currency of my country. It is now cash sitting there in my exchange account. Next I login to the exchange and wire transfer the money directly to my bank. Its there FAST, but I usually have to wait a few hours (2-3) until they release the funds as liquid. My longstanding relationship with bank likely makes it happen at above average speed. Also that is why my bank waives any wire transfer charges. I find it simple. The price I get for my BTC sold depends on the market conditions. We all know that we want to sell when the market is HIGH and that is my goal obviously! My .02