That is a great question!
Couple of points:
1. We know that the elect are out there. We sow the seeds, the Holy Spirit acts on those who are elect. It is often said that true Calvinists preach the Gospel promiscuously to all persons, aware that God alone knows those who belong to Him.
2. In scripture we see that God uses us to spread the Gospel to the elect.
3. We are commanded to spread the Gospel.
4. It has been said that if God had painted a yellow stripe up the backs of the elect, we would go around lifting up coats and preaching only to those with the stripe. We don't know who the elect are, so we preach to all. (widely attributed to Spurgeon, but there are no primary sources to prove that.)
Hope that helps.
So the rest of us need not bother with church.... you're right.. I'm heading to a bar to get a drink......