If you buy when you can, then don't feel bad.
For myself, I have never bought a single yaoi manga without reading if first (there is some real crap out there). Sites like this let me read it, so I know if I'm willing to drop money on it. If I like it, I buy it. But the author isn't losing my revenue, because I wouldn't be buying it anyway (and I never click ads).
I found "To Take an Enemy's Heart" on this site. Fell in love. Then I went to Tappytoons to buy the chapters. Then someone in the comments on this site, said that there was a hardcopy available on amazon. I went right over and purchased all the volumes.
Creators may not like it, but sites like this serve a purpose.
I am surprised to see how many people weren't aware of the fact that just how much illegal sites make off of others' works. I try to buy mangas whenever I can, but the reality is that I am not able to always buy books, even though it's unfair, I am still going to keep reading on mangago :-( I feel like a trash.