Goldman Sachs seem to be saying peak at 5k then halve. But then what do they know?

My guess is liquidity is much better shortly before the peak, so that it is easier to get money out of exchanges then.

I was wondering, if a 'whale' decided to sell 1,000 coins now and get the money out, how easy would that actually be in practice?
I understand Bitfinex have a 50k withdrawal limit.
In addition, is there real liquidity (ie, actual new dollar money entering the exchange) to allow for this size of exit?

Perhaps in reality the only way a whale could exit at the top of a price spike would be to slowly exit as the price rose, mopping up the new money entering the system.