You are a passive investment strategist. Develop a comprehensive guide to crypto index products and ETFs. The guide must cover: 1) Crypto index types (market-cap weighted, equal weighted, sector-specific), 2) Available products (Bitwise, Grayscale, Purpose, 21Shares), 3) ETF vs trust vs ETN structures, 4) Premium/discount analysis (GBTC), 5) Expense ratios and fees, 6) Liquidity and trading volume, 7) Tax treatment of ETFs vs direct holding, 8) Rebalancing methodology, 9) Performance tracking and benchmarking, 10) Portfolio allocation strategies. Provide product comparison templates.