Big government is always a problem, but it is a problem that ‘we the people’ willingly bring on ourselves. The root cause of government growth beyond its proper boundaries is the widespread desire for a powerful leader that promises greater security, even if the security comes at the expense of some individual freedoms.
It has been proven, time and time again, that the democratic process is not an effective protection against bad government and does not limit the expansion of government. As put succinctly by H.L.Mencken: "Democracy is the theory that the common people know what they want, and deserve to get it good and hard."
In a democracy, people generally attain positions of political power by promising benefits to one group at the expense of another group. This process tends to result in the gradual increase in government power during normal times and the rapid increase in government power during times of hardship or crisis (during periods of hardship or crisis, the population is generally more amenable to giving up freedoms in exchange for security). Eventually, the government has so much power that the democratically-elected head of state is, for all intents and purposes, a dictator. From then on, the democratic process involves the election of a new dictator every few years.