I don't understand why people claim it's a ponzi. No yield farm is a ponzi. the goal is to get the highest amount of liquidity possible in order to generate the highest trading fees.
There is a fact: liquidity attracts liquidity. Therefore adding incentive to LPs is a good way to get started.
People need to think about it this way. CUB - BUSD has a pool with massive liquidity. If no one trades CUB, price is fixed according to the ratio.
Then there is another pool with lots of liquidity, CUB - BNB. Again, in a world where no one trades, nothing happens.
However, we know BNB is volatile, basically like all cryptos. As BNB's price moves on exchanges, you automatically get an arbitrage opportunity through cub. For instance, if BNB goes up in price, while the ratio in the CUB - BNB pool remains the same, then CUB becomes valued higher in that pool then in the CUB - BUSD pool.
Arbitrageurs can immediately buy CUB using the CUB - BUSD pool and then sell CUB for BNB in the CUB - BNB pool. If they sell the BNB for BUSD, they will end up with more BUSD then they started with, completing the arbitrage.
Meanwhile those trades generate fees for liquidity providers. The higher the liquidity in the CUB pools, the more money is needed to arbitrage the prices. Therefore, more fees.
I don't see how this can be qualified of a ponzi. Or any yield farm for that matter. It is very speculative, yes, because people chase the incentive yield and not the trading fees. But at the core of the yield farming business, there are fundamentals, something everybody tends to forget.