Price to Book (P/B) of any equity trades >1x when the expected Return on Equity (ROE) is greater than the Cost of Equity.
The ROE of Bitcoin Treasury Companies can be greater than $BTC ARR, if the cost of leverage is lower than $BTC ARR. This is how leverage works for purchasing any asset.
GBTC had no ability to take on leverage. It didn't have optionality with its capital structure or operations. Plus, it had a drag from its management fees.