Benefits of SSL?

I have started my radiostation on http. I have spread the word about
the radio with a http-link. Now I (think I) have learned how to use my
letsencrypt certificate, but if I change now, I will break a lot of
links.

What I have done now is to redirect the https-links on my server to
https, so you can use both http and https in front of the url to the
stream.

That means you CAN access it via http. Is that a security risk? 

I don't know much about security, but I don't see any delicate
information we need to hide in the stream. 

So, why use SSL?