Just because you enter seminary does not mean you are going to be a priest. Seminary is a place to more deeply discern God’s call in your life. Discernment is a process that normally takes years to understand where God is calling you. That may be to the priesthood or not. If you go to seminary and you discern that God is not calling you to the priesthood, it is not a waste of time. Seminary makes everyone a better man, helps them grow closer to Christ, and gives you skills to help spread the Gospel.