I consider the 'bid' bots pretty much the same, but with higher risk. You could actually loose your a portion of your investment.

My thought process on reasonable returns is that I would like to receive back the SBD that I put in, so I could use it for other things, while gaining SP. Maybe my standards are too high, but for a paid-for upvote, that's the minimum I would want. I agree that earning SP is worthwhile, I just think it's better earned by curation rewards and organic (freely offered) upvotes.

Thank you for your comments, trusted doctor @catweasel.