> Why would people no longer mining make bitcoin useless? Because mining is what secures the network. > which IIRC isn't related to transactional processing

> Why would people no longer mining make bitcoin useless? Because mining is what secures the network. > which IIRC isn't related to transactional processing Transactions are confirmed by being included in mined blocks. The amount of compute power burned to mine that block, and the following blocks, is what prevents someone from pretending a different transaction (moving the money somewhere else - a double-spend) happened first. > what is the lightning network about? Isn't that a code change? Software running on top of the existing mining network, although downwards-compatible changes were made to enable it. The downwards-compatible is key here. > if every major exchange enforced the switch, and miners kept mining coins that the exchanges didn't take, Then someone would make an exchange that still trades "original Bitcoin" and get rich, and the exchanges would go bankrupt. More sensible and less controversial changes failed or resulted in splits (with the chain that remained downwards compatible being the most valuable one). (Downwards compatible is the easiest approximation I can come up with for the much more complicated reality.)