I understand you have to download the entire blockchain and sync in the beginning but don't you also have to constantly keep the software on if you want to buy/sell stuff, which means more data being downloaded to my personal comp every instant there is a transaction.
If this is true, what is the average amount of data per month being downloaded so that I can use bitcoin.
Also if this is true, why isn't this point highlighted on bitcoin.org, they say you have to initially download the blockchain but not that its constantly going to be downloading data on your comp, data is expensive!