RE: Is Steem a ponzi scheme?
Not a problem at all. I agree that the upvote bots are a reckless use of SP. The point of the vesting schedule is that the owner of SP is supposed to suffer the long term consequences of how the stake is used, and people's willingness to rent out their SP through vote bots confirm to me that we need either a much longer vesting schedule or a lot more education about the relevant economics (maybe both).
It's conceivable that bid bots could be used by charitable people to amplify the SP with which they upvote quality content and grow the network, but the economic incentives involved strongly favor abusive use instead.
I also certainly agree that Steem is not inherently a Ponzi scheme, and that it isn't currently a Ponzi scheme in practice. I just think people should recognize that all it would take for it to become one is for people to vote predominately for dividends rather than wages/reinvestment.