Why is upgrading your MacBook a good idea?
Apple would love you to buy a new MacBook every 3 years and has made it impossible for new models to be upgraded. If you have a Macbook from 2015 or before (with acception of the 12 inch MacBook) you have good options to upgrade your MacBook. The older unibody MacBooks from 2012 and before can be upgraded with both SSD and Memory making them run like a new one! MacBook Pro Retina's can upgrade the storage by replacing the SSD drive or alternatively use an iSlice with a large Micro SD memory card. Why spend money on a new Mac when you can get a few more years out of your current one?
Upgrade SATA to SSD drive
Expand Storage capacity
Add extra RAM (Memory)