Your wording is not quite right when you say they preach the gospel to the elect and non-elect alike. Nobody but God knows who the elect are. Calvinists preach the gospel to everyone period as the great commission teaches.
Calvinism makes a man humble, by reminding him that he isn't God. For many mysteries of life, we have only the character of God as our answer, as did Job. We know that God is good. Sometimes, that conviction is the only coherent element in our lives.
Grace is amazing, since God extends it to the most surprising and unsuitable people, such as me.
The issue is sovereignty. Ever since the fall, we've had these illusions about the feasibility of being our own gods, of enjoying autonomy.
Indeed, and perhaps many times to the same person, because God has a time of salvation for His elect ...