Did JRR Tolkien Destroy His Own Work?

This video is a response to a viewer comment on one of my earlier videos (Is Tolkien's Middle Earth supposed to be our world?). He suggested that Tolkien had ruined the Middle Earth by setting it in the real world. I wanted to give a detailed personal response because I was also very disappointed when I found out the Middle Earth was essentially supposed to be a prequel to our own world. Since it doesn't obviously connect to the real world, the implication is that all the fictitious history of Middle Earth just got completely wiped, and that would be a bad ending if it were the case. To resolve this issue, it's necessary to get into Tolkien's thought process, and what exactly his Middle Earth mythology is supposed to connect to, as well as how.

This was an unscripted video which went longer than usual for this channel. I did quote from some of JRR Tolkien's letters, but apart from that I just wanted to draw from my memory without looking at anything so that 1) the response would be more authentic, and 2) I can practice my recall.