After doing some research, here’s what I found. (All open to correction if there are errors) The upper bound for outputs per block is ~32k using P2WPKH batching. Which equates to 4.6M UTXOs per day, 138M month, 1.68B year. Using 120bytes per UTXO, that’s 16-18GB/month and 200-230GB/yr. Legacy P2PKH and taproot are somewhat less, but still 200GB and 150GB / year. Current UTXO set size is 12-13GB. Annual cost depends on fee rate. At 100 sat/vB, it’s 52,560BTC. At 500 sat/vB, it’s 262,800BTC. Or $10.5B and $52.6B at $200k/BTC.