Is it a sin to go to the Saturday Vigil Mass instead of the Sunday morning Mass when you could easily make it to the Sunday morning Mass?
No, it’s not a sin.
No it’s not
No, it’s not a sin, simply a matter of choice.
Could you say something about why you think it might be a sin to attend Mass on Saturday evening rather than Sunday? Why do you think parishes offer Saturday evening Masses if it would be a sin for people to attend them?
Not a sin. The attendance rule is a Saturday night mass OR Sunday. Both are equally permissible.
Can. 1247 On Sundays and other holy days of obligation, the faithful are obliged to participate in the Mass.
Moreover, they are to abstain from those works and aVairs which hinder the worship to be rendered to God, the joy proper to the Lord’s day, or the suitable relaxation of mind and body.
Can. 1248 §1. A person who assists at a Mass celebrated anywhere in a Catholic rite either on the feast day itself or in the evening of the preceding day satisfies the obligation of participating in the Mass.