It's very simple. The whole time bitconnect ran, the BCC price went up a lot faster than the interest they were paying. Including the capital releases, the lending was profitable for bitconnect as they were accumulating more and more BCC coins and paying out less BCC than the amount loaned to them.
Nobody is disputing this. The people who run Ponzi scams make a profit from it. That's why they run them.
Assuming they had zero BCC reserves (although they actually had millions) they wouldn't need to use BCC from new investors to pay the interest so it wasn't a ponzi!
That is only true if the price of the token keeps going up forever. Eventually the price stops going up. After that the scammers need to either start giving back some of their profits or close down the scam. From their point of view the most profitable thing to do is to close down the scam. That's what happened.
While the price was high they didn't "need" to sell any of their tokens, but since selling their tokens was their only way of profiting from the scam, and since they knew the price of the tokens would drop massively as soon as they shut down their scam, of course they were selling their tokens. They didn't "need" to, unless they actually wanted to make a profit from running their Ponzi scam.
Regarding affiliates, remember the BCC loaned to bitconnect could also be staked by them (8% a month or so).
Staking is a zero sum game. There is no reason it should increase market cap, and so it should tend to cause the price per unit to fall in proportion to the corresponding increase in money supply.