we will have a war or pandemic, nature has its checks and balances.
In 1918 the Spanish Flu killed between 20 and 40 million world wide, in 1 year. It made the Black Death look like a hiccup epidemic. The reason is unknown, but it tended to hit younger, healthy men the hardest, the exact opposite of most diseases.
A round of this could completely eliminate California which would really check their balance.