Some are delegating not to get any returns for their investment instead they are sending donations as support.

But you are paying them like any normal delegator.

You are promoting a service, you are at the top of Steem's trending page, when somebody visits steemit.com they see your post first. So, you claims should match with what you are doing.

You 20% extra is like me saying I'll be sending you 100 steem but I am sending it to myself (or other party) on behalf of you. Believe me you received 100 steem.

Please do not try to sell apples by saying you are selling oranges. If you cannot show that your claims are true please refrain from such advertising.

I am waiting to see how your math works.