Bitcoin has successfully defended the ETF cost basis level around $81,500 twice, establishing it as a critical support zone after trading below this benchmark for most of the year. Glassnode data indicates that previous rallies, including the May rebound, were capped beneath this threshold, making the current hold technically significant. A breakdown below $81,500 would expose Bitcoin to the next major support level at the true market mean of approximately $77,500. Maintaining the ETF cost basis as support remains essential for sustaining upward momentum and avoiding a deeper correction toward lower valuation bands.