Recently, I wrote an article in which I was enthusiastic about Bitcoin ETFs, and more specifically BITO.Since BITO is backed by futures contracts, contango bleed is a huge factor that influences the tracking error of this ETF.Also, BITO suffers from a limit on the number of futures the fund is allowed to hold, which might increase the tracking error.Physically-backed Bitcoin ETFs are the future, not ETFs backed by futures contracts.