I don't think this is to do with conversion necessarily. I think you have a color space issue.
Lightroom uses Prophoto RGB as its default color space. I don't use Elements, but have Googled a little and it seems that it only offers sRGB or AdobeRGB. Others may well know more....
Whichever way, you need to match the color spaces in both programs. The shift above is caused by the two programs interpreting the colors in your images differently as they are using different "algorithms" to process color information.
If my supposition above is correct, I would suggest that you set the color space in both Lightroom and Elements to AdobeRGB.
Since when does posting on social media amount to "giving work away?" I don't think I did.
I should point out that if your costs of obtaining a great image are exceeding that image's earning potential in the market...... That is also capitalism.
I am also not suggesting that anyone should allow people to use images for free. However art and picture editors will increasingly look at social media as a source for obtaining images as supposed to the "old way" of sourcing images which was contacting people that they knew. Perhaps reductions in image sales volumes is due to people not engaging with this process?
What I am suggesting is that we should use Facebook and other media creatively as advertising outlets for our images.
Your court case raised around £1400. I have been lucky enough to have made considerably more than that on single image sales where the purchasers originally found the images on Facebook! And I didn't need to go to court! Sure there is some unlicensed use, but the licensed use more than recompenses me for this.
I think it depends on how you view your business/creative model. You could keep all your images in a folder on your computer and never post them anywhere-they would be 100% safe from theft, but you are unlikely to sell many
A great image will make significant amounts of money, on top of the unpaid for use that we are all so afraid of! I think we need to re-configure our thoughts on sharing images, and look at the "lost" revenues that you do not get as a marketing cost. Putting ugly watermarks across the center of our images diminishes their effect and will result in less sales..... I think using watermarks that do not detract significantly from the image and ensuring that whenever possible, your metadata contains your copyright is still the best option.
I have sold a fair number of images on the back of people seeing them on Facebook and the like-these sites represent an amazing "shop window". I think we should embrace this and use it to our advantage. They aren't going away and if you don't do it, your competitors will.....