As you can see in Section 5: Your Content, you have already consented to following:
You retain any ownership rights you have in Your Content, but you grant Reddit the following license to use that Content:
When Your Content is created with or submitted to the Services, you grant us a worldwide, royalty-free, perpetual, irrevocable, non-exclusive, transferable, and sublicensable license to use, copy, modify, adapt, prepare derivative works of, distribute, store, perform, and display Your Content and any name, username, voice, or likeness provided in connection with Your Content in all media formats and channels now known or later developed anywhere in the world. This license includes the right for us to make Your Content available for syndication, broadcast, distribution, or publication by other companies, organizations, or individuals who partner with Reddit.
No. Just claiming your own rules over existing rules is the same crap that those sovereign citizens are trying to pull. As much as I hate reddit (being an now ex 13year redditor) this is not something you fix plby putting your own license in your post, it makes you look ... Well, like those sovereign citizen types. Dumb.
Yeah you really don't seem to understand how any of that works.
If you use a platform and that platform specifically states that they have rights to use your "work" if you post there, then they can. For one, if they couldn't, then they wouldn't be able to display your comment to begin with.
They can add in their terms of usage that they are allowed to do more with your work, like analyze it for personalized ads, for example.
You adding your license thingie in your message is a cute way to try to say "no you can't!" But yeeaaaahhh, that's not how anything works. You can't simply make a license that invalidates the terms of service of a website. It's literally the same nonsense that those sovereign citizen idiots try to pull with police and government (and always fail in hilarious ways)