[ChrisClark]

Though, the 24 hour trading volume for ETH is $1.5 Billion USD. So it won't affect the price as much as you'd think.

[imron]

$1.5 Billion, made up of many smaller transactions (~USD 15.5k on average according to this site [0]).

A number of large transactions to convert that much ETH to USD, would significantly affect speculator confidence, triggering others to sell.

0: https://bitinfocharts.com/ethereum/