I share your concerns Thomasar. I'm yet to upload on Steemit over these fears. Would be great if there was some kinda image protection on here. Maybe just the Photography blog with right-click disallowed the same way 500px.com implements; the users copyright appears instead of 'save image as'. Here's an informative article on appropriate image size to minimise the thieving scumbags plagiarism! Great photo sir :)
https://www.plagiarismtoday.com/2014/08/28/size-online-images-uploaded-avoid-theft/
edit: Just found this article on progressive blockchain ICO's. Let's hope for a better future protecting all 'original' artwork. https://medium.com/@davidarianik/blockchain-probably-save-photographers-4459cfcb9535