Many errors are made by assuming that things scale linearly when they don’t. For example, if you triple your speed on the highway (from 35 mph to 105 mph), you probably won’t triple the mileage you cover in an hour. You’ll likely spend plenty of time parked on the shoulder, explaining to a police officer why you were driving so fast.
One of the most frequent and unfortunate failures to understand that things don’t always scale linearly involves democracy. Too many people assume that what holds true for their book club or homeowners association holds true for democratic polities of millions of people.