Assets in the Grayscale Bitcoin Trust fund have dipped to $18.3 billion as competitors charge fees as low as 0.20% compared to this fund’s unusually high 1.50% fee, Barron’s reports.

That’s a $2.4 billion decline in Grayscale Bitcoin Trust assets from $20.7 billion on Jan. 31, according to Morningstar. Since the fund has soared by 49% this year, the asset level understates just how high the outflows have been.

This expense ratio translates to more than $300 million a year that Grayscale is collecting on this exchange-traded product.

In January, the Securities and Exchange Commission approved a slew of far less expensive Bitcoin funds by competing asset managers, including the iShares Bitcoin Trust and Fidelity Wise Origin Bitcoin, which each charge a 0.25% fee. Also greenlighted were the ARK 21Shares Bitcoin (0.21%) and Bitwise Bitcoin (0.20%) funds.

Three of these managers have fee waivers that bring the iShares Bitcoin Trust fund’s fee down to 0.12%, and the Bitwise Bitcoin fund down to zero. Fidelity is waiving its entire fee on the Wise Origin Bitcoin fund through July 31.

The rub for investors is that these investment products are not typically offered in tax-deferred retirement plans. Many bitcoin funds have tremendous gains and are subject to capital gains of 20% for long-term investors and 37% for investors of less than a year who cash out.

This is keeping many Grayscale Bitcoin fund investors from redeeming their shares of the fund, which has traded since September 2013 and has a 61.2% 10-year annualized return.

Grayscale is able to continue charging its five-times higher fee to its shareholders because its fund is an exchange-traded product, which falls under the Securities Act of 1933 and the Exchange Act of 1934. These regulations do not offer investors fiduciary protections.

Regular exchange-traded funds that invest in stocks and bonds are governed by the Investment Company Act of 1940, which requires “the investment adviser of a registered investment company to have a fiduciary duty with respect to the receipt of compensation for services.”

That means that the money managers’ board of directors must consider whether fees are excessive.

In 2010, the Supreme Court ruled a fund fee would be considered excessive if it were “so disproportionately large that it bears no reasonable relationship to the services rendered and could not have been the product of arm’s length bargaining.”

Normally, investors in funds who believe they are being charged too much sue, but such a lawsuit would not fly for these ETPs.

It will be interesting to see whether more Grayscale Bitcoin fund investors decide to take their profits off the table, pay the capital gains tax, and move to one of its competitors.