In fact, if there wasn't the option to attack leading to reduced income, it's highly likely that quite a few players would have adopted the strategy of accumulating money until the very last turn to use it.
That is why, while it might seem like Kain only made the simple choice of bidding 0 gold coins each time, the considerations involved were absolutely not few.
"Kain, for the next three turns, you can comfortably accumulate gold coins, but once that alliance successfully retreats with full pockets and is no longer maintaining the winning streak, you will definitely become the target for everyone to aim at."
"I wonder, will you abandon the accumulation strategy, or will you break through the increasingly tightening siege?"
...
Cyrus looked at the current situation with some contemplation.
He was hoping that the factions would spend more in this turn 2 bid, but he didn't expect this outcome.
"Something strange is going on."
This thought flashed through Cyrus's mind.
