Even with a cleared mempool the fees to transfer btc from an exchange like nostr:npub1p3gswdvpvw5n2rgnlwsvmhvn7fufsqguuwvguwykgdwkh5p8uuesdlgpzg is more than $40. Meanwhile nostr:npub1ex7mdykw786qxvmtuls208uyxmn0hse95rfwsarvfde5yg6wy7jq6qvyt9 offers free withdrawals. Pretty easy choice