If you do not obey the laws, what will happen to you?
Usually nothing. Most citizens of most modern societies break some laws routinely, frequently through ignorance. Ask any cop; if he follows you around for a couple of hours, he can find something to arrest you for. Lawmaking being pretty inefficient, much law is badly written and widely ignored in both directions.
But you could rightly call that evasive nitpicking on my part; you meant "government power over individual citizens is backed by overwhelming force." This is completely true... and does not refute my point. A government possesses stability and security precisely to the extent that they do not use this power. Laws are either made with the consent of the governed... or they demand increasing escalation of enforcement. This only works until you've escalated so far that the force undermines the structures that you're using to deliver force with... at which point the country usually collapses.
(Zimbabwe's a pretty good near-worst-possible-case example.)
Short form: The government does not have the power to escalate indefinitely... because indefinite escalation tends towards destroying the society that the government is part of. Governments that survive do so in part because they know this, and limit their use of force to well below this point.
This is a statistical process, not an absolute one. Large and important results can be achieved by force, and injustice based on massive use of force can and does exist. But the trend is away: the more a law depends on force to execute it, the less popular it is, the greater the pressure away.
(My government has the ability to escalate any dispute with me until I am in prison or dead. But it doesn't have the ability to escalate a dispute with the population as a whole until the entire population is in prison or dead.)
Authoritarian states, backed entirely by use of force, are less stable and, ultimately, less successful. Force is the short-termm solution; long term it loses out.