He/She could have scam with high quality content, it doesn't change anything to the equation, content quality is not relevant here
I'm not getting it. High quality content is the intended outcome.
create fake account, upvote it, boom, the fake account earn few hundreds
This is not a scam! It is part of the advertised and intended value of SP that authors can vote up their own content. If an author thinks the material is good and will get a following, we want them to buy SP in order to vote it up and promote it (buying SD to used the "Promoted" feature is another option).
The system mechanism is supposed to (and does) ensure that self-promoted content earns only substandard rewards (and possibly none at all if the content is so bad/abusive as to be downvoted). In order to earn good rewards (i.e. sustain a good return-on-investment on the SP that you bought) it is necessary that others vote for it as well.
In the context, by high quality content I mean content that could have fit the taste of razvanelulmarin,
It is not what I intended to mean :( I'm not talking about self upvoting in that sense. Let me rephrase. I think that if a malicious whale wants to make easy cash without cashing out his whale account, he can simply create a secondary (minion) account with which he will start posting content. Then with his whale account he will upvote his minion account. It is a kind of "pump and dump scheme" adapted to blogging.
I understand what you are saying. The system is supposed to handle that. I think it is simplest to say that the system apparently worked in this case. People being vigilant, identifying plagiarism, and downvoting it is part of how it supposed to work.