Quote from: gjarreau on September 09, 2014, 10:51:11 AM

Thank you for answering my earlier questions. One thing that struck me in an earlier post (and having listened to podcasts), was the fact that some other alt-coins ride the block-chain. I assume by using it, they enlarge it, making it harder to d/l and store. Isn't this a "tragedy of the commons" scenario?

The blockchain has limits built into it that limit how quickly it can grow.

Unless the protocol is modified int he future, currently a block must be smaller than 1 megabyte. Any block larger than that would be considered "invalid" and would be rejected by all miners and nodes.

Blocks are created on average every 10 minutes.

This means that with the protocol the way it is today, the fastest that the blockchain can grow is a bit more than 144 megabytes a day or somewhere around 53 gigabytes per year.

Of course at the moment we are not yet anywhere near the maximum growth rate of the blockchain. After nearly 6 years of existence, the blockchain is currently less than 22 gigabytes. That's an average of less than 4 gigabytes per year.

While services that attempt to build on top of the blockchain may add a few more transaction to a block, they also increase the utility and therefore the value of bitcoin. Furthermore, to get those transactions confirmed quickly they need to pay transaction fees in bitcoins. This adds to the bitcoin economy and increases the revenue for the miners.