The short answer is yes: you could bet in BTC because FTX pools collateral across all positions: https://help.ftx.com/hc/en-us/articles/360027946371-Margin-Collateral
The short answer is yes: you could bet in BTC because FTX pools collateral across all positions: https://help.ftx.com/hc/en-us/articles/360027946371-Margin-Collateral