Trezor's Chief Business Officer, Danny Sanders, expressed concerns at the BTC Prague event about the growing trend of holding Bitcoin in ETFs, which he views as detrimental to the core principle of self-custody. Sanders highlighted that only about 10% of the estimated 600 million global crypto users practice self-custody, with a mere 12 to 13 million utilizing hardware wallets. He emphasized the need for the industry to address psychological barriers to self-custody by developing more user-friendly products and educational tools, rather than promoting reliance on intermediaries like ETFs.