For the main chain to update every node, it consumes a lot of energy. There's no need to have that level of security for small transactions. It makes sense to use a second layer. The main chain will be expensive and therefore will be used where the utmost certainty and security is needed. I don't need the entire network to verify my zap or coffee purchase. I like the thesis put forward in the bitcoin standard. Makes a lot of sense to me. What are your thoughts?