If Bitcoin price pumps from $1300 to $3000 in few hours, nobody would make profit from it, because the exchanges wouldn't allow you to sell your Bitcoins and make the fast profit, it would bring a big loss for exchange sites.
Do you agree with this?
If exchange itself is not trading, they basically don't care
More specifically, they care for fees, and trading fees obviously come from trades, so when there are abrupt price movements the trading volume spikes too. And it doesn't matter whether the price flash crashes or flash surges. So, they are in fact interested in volatility and price being "alive", therefore prices pumping to 3,000 dollars per coin would provide exactly that, i.e. insane levels of volatility
1. Most fees are a percentage, so higher price, higher fee
2. When one analyses the fee structure, it will show that a sellingfee is a higher percentage than a buying fee.