I don't understand all of the "scam" criticisms, particularly from a user perspective. In that regard, it's absolutely not a scam.
From that same perspective, however, there certainly is the perception that the system is being abused. There has been a considerable amount of frustration about trending content and "whale" voting that isn't being seriously discussed. I think that's turning a lot of people off and discouraging some very good writers. Ned, Dan, and the other whales should try to do more to address that - even if it's only perception. It can still be damaging to the platform overall and ought to be taken seriously.
But, no - there is no scam. There's no requirement to invest in this in order to participate and the rewards are in fact real.
Sure, that is another topic and it may very well be a valid criticism. However, I believe that Ned and Dan are indeed already considering making changes. @dantheman has been writing fervently about possible other voting mechanisms and algorithms.
Great thoughts overall here, friend.