[uncensored-r/Bitcoin] Are NegocieCoins and TemBTC exchanges a potential scam?

The following post by carloscgabriel is being replicated because the post has been silently removed.

The original post can be found(in censored form) at this link:

np.reddit.com/r/ Bitcoin/comments/bm8d1j

The original post's content was as follows:

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So, NegocieCoins recently made up to 1st place in adjusted volume in CMC. A Brazilian exchange, relying only in BRL/BTC trades.
I`m from Brazil and already made some arbitration trades between NegocieCoins and TemBTC - it was the easiest way to earn money I have ever faced. This raised a red flag, and I dug deeper into understanding this.

My findings are that this smells, taste, feels and looks like a scam. I´ll provide below all the steps I took to understand this.

Initially, I´ll explain how earning money using these exchanges works (and today, May 8th 2019, it still works):
Here are two screenshots I took from both exchanges (around 9:00am May 8th 2019 - Brazil time), to use as the example:

https://ibb.co/Qnz9F03
https://ibb.co/q0ZRbPm

1st: You deposit BTC on the NegocieCoins exchange - let´s say 1 BTC.
2nd: You sell the BTC for BRL at the current market price. Considering the 0,5% Taker fee, you get BRL 24354,48
3rd: You transfer the BRL amount to TemBTC using the Fortknox option (it`s na internal transfer process between these two exchanges, so you dont need a checkings account or anything like it in Brazil to perform this transfer). This has a 0,5% fee, so you get BRL 24232,70 at TemBTC exchange.
4th: You buy BTC at the current market price. Considering the 0,5% Taker fee, you get 1,00182054 BTC.
5th: You transfer the BTCs back to NegocieCoins exchange. Considering the 0,0003 BTC fee, you get 1,00152054 BTC back at the NegocieCoins exchange. Easy 0,152% profit. And you can start all over again. You can perform this operation many times a day.

It always work because the spread between the buy price at NegocieCoins and the sell price at TemBTC are always the same. When one changes, the other changes as well. The spread is always 1,7%.
You can check the books directly at:
https://www.tembtc.com.br/negociacoes
https://www.negociecoins.com.br/negociacoes

Also, the prices are relatively stable. They seldom change at an interval lower than 15 minutes. There is a risk that the price change in the middle of an operation, in this case you can have a loss or a higher profit, but in the  average, you get the 0,152% profit. Also, you can try to increase your earnings if be a Maker instead of a Taker. The Maker fee is 0,3% in both exchanges.

So, easy to get money, right? Now, I list the reasons why I think this is a scam:
1st: There is no easy, guaranteed and honest way to earn money in the financial market.
2nd: Both TemBTC and NegocieCoins belongs to the same owner: BitCoin Banco: https://www.btc-banco.com/
3rd: There is no actual movement of BRL currency during this operation. Even if you have a checking account in Brazil and you want to withdraw the money from NegocieCoins and then deposit it in the TemBTC (instead of using the FortKnox process), the withdraw fee (which is 0,9% + BRL 8,9) would not make the operation profitable.
4th: Even though the BTCs can be transferred between exchanges both by blockchain or Fortknox subject to the same fee, it shouldn`t be a problem for them to transact the BTCs through blockchain, since the inflow of BTCs is likely huge as most people in the cripto market has no access to BRL. So they have plenty of BTCs.
5th: Why wouldn`t BitCoin Banco just match their TemBTC book and NegocieCoins book if the orders are authentic?
6th: Why wouldn`t the BTC buyers at NegocieCoins buy them at TemBTC? They like to pay more for it?
7th: BRL withdraws are recently taking too long to process. Around 2 business days. This is weird, as Brazil  uses a process of money transfer between checkings accounts that takes around 5 minutes to process.
8th: The orders in both TemBTC and NegocieCoins exchanges are huge. And they don`t compete. The price is exactly the same for the several first orders.
9th: The spread between the buy price at NegocieCoins and the sell price at TemBTC are always the same: 1,7%. You can check it now using the links I provided above.

So, my theory is that they are creating this "easy way to earn money" to get a huge inflow of BTCs and some BRL to them.
And since they don`t usually transact their BRL, they can fake the accounting and maintain this costly spread to bring more and more BTC and money in.

This is just a theory. I don`t work there, don`t know anyone who works there and don`t have any insider information.

I recently saw a video from someone saying that the BitCoin banco CEO said in a Brazilian event that the huge amounts in the NegocieCoins books are maintained by contracts he has with people and companies that are obliged to buy BTC at the price defined by the exchange.
I also don`t know if this is true or not, but who would do this kind of contract? A contract to make you lose money? Also weird.

In case I have new findings, I´ll add to this post. Please let me know your thoughts and possible theories where this would not be a scam.