My situation is that I also have IBIT/FBTC.
The story was that I bought GBTC in 2019/2020 in IRAs and Roth (the date is to the best of my recollection, maybe even early 2018) when btc was at $8-10K.

Later on, I exchanged it to IBIT/FBTC at par when everyone was screaming about how GBTC is going down the drain.
Now, it is quite a bit of $$ equivalent and about half is in Roth, hence no taxes on sale and withdrawal.

It is possible that I would shave some portion of this anywhere between 180 and 200K/btc (150K is too low).

I don't plan on selling any bitcoin...I am thinking similar to @Searing-trusts, legacy, etc.