Personally, I think that doing always the same giveaway brings the people to "ignore" the post itself, that's why there are simple comments (I'm one of the guilty ones).
My advice is to mix different types of giveaways/raffles, maybe when you giveaway common cards, it can be a simple "I'm in" giveaway, when you give away bigger prizes, there should be more rules...it could be helpful to slightly change the graphic, so people can notice that's there is something different from one giveaway to another and they will be interested in reading the "new rules" (or you could just write the rules in the graphic itself).
I think that you are doing a nice and kind job, so I'm sorry that you feel like this, but giveaways mostly attract "small" players and multi-account players, who just don't mind about anything else than winning cards for free.
I want to say thank you for all the effort and money you are putting into these giveaways, I wrote these advice only because you asked, I honestly think that you are doing a great job.
As you can see from the comments section, people are "distracted"