Big government does tend to spend wastefully.because there is very little if any accountability.For example,millions of dollars can be wasted or misspent without anyone ever really knowing.This is why audits are constantly needed when any type of government spending is taking place so controls of some sort can be put in place.
Big governments tend to have bloated programs that are mishandled by people who are paid too much. In addition, big governments also often spend too much on military. Those who go to war like the United States spend an exponential amount more. All of these things needlessly add to a debt which cripples the country's future.