The first-ever Bitcoin ETF listed in the United States is finally here!The ProShares Bitcoin Strategy ETF (BITO) will invest in Bitcoin futures contracts, not Bitcoin itself.Investing in "physical" Bitcoin would be the better investment for a Bitcoin ETF, but the SEC has not yet shown a willingness to approve that structure.Using futures exposes the fund to disconnects with the underlying value of Bitcoin as well as roll costs.Overall, it's not the best structure for Bitcoin exposure, but it'll work for now.