Re: No diminshed sales
The "diminished sales" argument gets hashed out regularly by translators and fans, no true answer I think.
I'm registered on Mangadex as a reader but I also translate and contribute 'scanlated' manga to the site. A lot of the other manga aggregator sites out there survive by scraping and reformatting content from Mangadex since it supports a thriving translation community which posts their work on the site almost exclusively.
The series I choose to translate tend to be oddball mangas which are very unlikely to get commercial release in the West. This salves my conscience a little but I'm totally aware what I'm doing is copyright theft.