WordPress have an old article (The $64,000 Question: WordPress.com or WordPress.org?) with an analogy that I’m going to borrow. The original article was written in 2013, although I see that it has been updated to mention the WordPress.com Business Plan (more on that below). I’ll extend the analogy a bit and throw in some things that weren’t mentioned.
The idea is that self-hosted WordPress versus WordPress.com is a bit like buying a house versus renting one. I like this comparision and would extend it to include other platforms such as Squarespace, Weebly and Wix.