Generally it is recommended to hold your own keys. But if the peak of the bull market is reached, you need to make a move somehow to get to sell.
If Bitcoin hits 200, 300k at the peak of the next bullrun alot of people will want to sell. Fees will be very high. Alot of exchanges had alot of problems, you couldnt sell because of technical issues, you couldnt withdraw because they suddenly demanded more and more KYC info without processing it, some exchanges stopped responding completely.
The only other way to sell bitcoin without exchanges would be maybe local bitcoin, but who would be comfortable meeting a stranger when it comes to a big amount of money
What were the most reliable exchanges during the madness of December 2017?
What is the best way to sell Bitcoin?
Register at Binance