The game needs some balancing. It's INCREDIBLY easy to get far more generators and smelters than the drones need / can support. Either the cost of drones needs to rise slower or there needs to be more upgrades for scrap to keep up purchase rates.
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You were right. I ran the economy through a simulator and the gap was even worse than it looked, by 100 drones the next drone cost about 1.6 million while the smelter you needed cost around 800.
The real problem was that generators and smelters hit a hard cliff, where past a certain point an extra one did literally nothing. They now give small diminishing returns instead, so overbuilding barely costs you. In simulation that closed most of the gap between playing carefully and just buying the cheapest thing.
Fix is in the build I just uploaded. Thanks for the report.