The population decay/growth mechanic is indeed quite broken right now - that's on me, and I’m sorry about that. The intention was not to punish players for reading upgrades, but to create tension where you have tools to slow down the population decline and boost its recovery and should choose and balance it with damage increasing
We are planning to rebalance and improve this in the post-jam build. For now, we are holding off on releasing updates until the Ludum Dare voting period is over, so everyone evaluates the fair version of the game.
Really appreciate your comment and feedback!