Again, the limits are not fixed, and therefore cannot be clearly defined. If a customer is spending $5K / month on dedicated servers, Hetzner might earn enough

Again, the limits are not fixed, and therefore cannot be clearly defined. If a customer is spending $5K / month on dedicated servers, Hetzner might earn enough from renting hardware to cover truly unlimited usage of bandwidth. If a customer is spending only $50 / month, that's a completely different case. Such a customer might simply be not valuable enough to keep.