U.S. spot Bitcoin ETFs took in $999 million on Sep. 21 and $714.7 million on Sep. 22.BTCS adviser Wojciech Kaszycki sees a rally that began with spot demand but is attracting leverage.He puts the next test at $90,000, where holders may sell after recovering earlier losses.Kaszycki says treasury companies should pace purchases and avoid borrowing against their Bitcoin.