To detect and reject a double spending event in a timely manner , one must have most past transactions of the coins in the transaction , which , naively implemented , requires each peer to have most past transactions , or most past transactions that occurred recently . If hundreds of millions of people are doing transactions , that is a lot of bandwidth each must know all , or a substantial part thereof . The bandwidth might not be as prohibitive as you think . A typical transaction would be about 400 bytes ECC is nicely compact . Each transaction has to be broadcast twice , so lets say 1 KB per transaction . Visa processed 37 billion transactions in FY 2008 , or an average of 100 million transactions per day . That many transactions would take 100 GB of bandwidth , or the size of 12 DVD or 2 HD quality movies , or about $ 18 worth of bandwidth at current prices . If the network were to get that big , it would take several years , and by then , sending 2 HD movies over the Internet would probably not seem like a big deal . This is a post about SPV wallets and allowing users to participate in the verification of individual transactions are they are broadcast over the network . This has absolutely nothing to do with the point and you would do well to read the posts before trying to use them as sources for your bullshit . This does not exempt miners from verifying all tx ' s . This is a post about bandwidth fucktard , we ' re talking about throughput . If you can ' t tell the difference no one should listen to you . Go ahead , again , show us the math behind small miners verifying two HD movies worth of data for 1 block . Please . We ' ve all been waiting for your side to do this . None of you can . It ' s just simple algebra . Show us the economic incentive for larger miners not to just fill blocks with transactions that belong to them and push small miners out of verifying transactions or including txs in blocks . Please . Show us these things . You can ' t . That ' s why your side loses .