under fidelity FBTC the OP does not own a share of BTC
he owns a share of a fidelity company share. he cannot redeem that share for actual BTC. he has no ownership rights of actual BTC
however yes using the 401k method to own shares EXPOSED to bitcoin PRICE. means he gets the exact same ups-down of the market movements, with for him the upside that he can purchase exposure amounts at a discount due to pre-tax share purchasing. and tax free selling of shares
but its still worth stating the OP does not have ownership rights over actual bitcoin.
With an ETF shareholders, admittedly only the larger ones, have a right to redemption meaning they can request delivery of the underlying asset. To simplify the Bitcoin ETF's it is a cash only redemption meaning you would get the spot market price of Bitcoin not physical Bitcoin but effectively it's the same thing. So with an ETF in a very real sense the shareholders are owners of the underlying asset and the fund manger, in this case Fidelity, is just a custodian. It's not as good as holding Bitcoin in your own wallet but has the advantage that you can get access to it through an IRA or 401k with a linked brokerage account.
i can tell you have not even read fidelity's s-1/a filing with the SEC..
there are too many corrections i would have to make to clarify where you have things mixed up, that its probably best you go read the s-1/a to realise that you as a share holder through a broker are several levels away from having any ownership claim of bitcoin. your shares are just measured on the performance of the bitcoin market index.. (you have exposure to spot price but not ownership claim of btc)
if not interested in reading the whole of it. and just want to learn some risks .. use browsers [find in page] function for "sole discretion" and see all the points where all the levels above you can do things without share holders permission/vote/knowledge or notice.. its enlightening
https://www.sec.gov/Archives/edgar/data/1852317/000119312524003839/d375081ds1a.htm#rom375081_4by the way its really worth learning what a trust is. its where there is no ownership. just a hierarchy of management and beneficiaries whom dont own the property inside the trust but can get beneficial benefit of the trust structure without ownership
ill just add this lil snippet
MANAGEMENT; VOTING BY SHAREHOLDERS
The Shareholders of the Trust take no part in the management or control, and have no voice in, the Trust’s operations or business. Except in limited circumstances, Shareholders will have no voting rights under the Trust Agreement.
and
The Sponsor will have full power and authority, in its sole discretion, without seeking the approval of the Trustee or the Shareholders (a) to establish and designate and to change in any manner and to fix such preferences, voting powers, rights, duties and privileges of the Trust as the Sponsor may from time to time determine, (b) to divide the beneficial interest in the Trust into an unlimited amount of shares, with or without par value, as the Sponsor will determine, (c) to issue shares without limitation as to number (including fractional shares), to such persons and for such amount of consideration, subject to any restriction set forth in the By-Laws, if any, at such time or times and on such terms as the Sponsor may deem appropriate, (d) to divide or combine the shares into a greater or lesser number without thereby materially changing the proportionate beneficial interest of the shares in the assets held, and (e) to take such other action with respect to the shares as the Sponsor may deem desirable.