their ETF is not the actual bitcoin price. but a SHARE price of the COMPANY(trust) the winkles own.
do not confuse the ETF with bitcoin. they are 2 different things.
...
now with that said. when/IF the ETF is released people may convert their retirement portfolio's to include ETF shares. (not affecting the bitcoin price)
Most ETFs (it is my understanding that COIN will be no different), allow certain Authorized Participants ("AP") to exchange shares of the ETF for the equivalent assets that those shares represent, and vice versa.
So for example, if the price of COIN were to go above the price of the equivalent amount of BTC that each share of COIN represents, (and there is sufficient liquidity), then someone might buy 5,000
BTC on an exchange, exchange those
BTC for shares of COIN, and sell the shares of COIN on the open market, and pocket the difference.
This is not unlike how a order on the OkCoin futures platform affects the price on other exchanges, provided that it is large enough, and the various exchanges have sufficient liquidity.