So [ the COIN fund will buy the coins from the Winkelvosses ] is your pure speculation.
Of course. What can we do except speculate?
As far as I know, they bought those bitcoin at 2 digits. If they wanted to sell, they could have sold anytime since late 2013 in the open market with sound profit. Why do they need to wait for SEC approval?
Perhaps because they expect the price to go up once the ETF is approved, for all the reasons that have been repeated so many times; where if they tried to sell 200'000 BTC on the open market the price would crash.
Why do you think they (or anyone) would want to create a bitcoin ETF?
Same question could be asked for any commodity ETF. One reason is to earn management fee. An ETF on NASDAQ will also significantly improve the liquidity of the bitcoin market and increase the value of their personal stash.
Well, the latter is almost the same thing as saying that they expect to sell their coins for a better price than if there was no ETF.
For the price and for the Winkles' profit, the effect of (Winkles seeling to the open market) and (COIN buying from the open market) should be almost the same as of (Winkles selling to COIN).
The Winkles do not have experience in fund management, why else would they go into that line business? The management fees are not stellar, and are hard to predict. How much did SMBIT collect in fees -- perhaps 5 million US$ in 15 months?
The real profit for fund creators comes from speculation -- from the sale of the underlying assets to the fund (i.e., indirectly, to those who buy fund shares) at better-than-market prices. See for example those funds that the banks created from packages of worthless mortgages, before the 2008 crisis.