Making Vows

In Scripture, the making of vows is taken seriously: 
"And the Lord said to Moses, 'Say to the people of Israel, When either a man or a woman makes a special vow, the vow of a Nazirite, to separate himself to the Lord, he shall separate himself from wine and strong drink.'" Numbers Ch. 6, vs. 2.


Vows are voluntary, but once made, they are regarded as binding, and are to be fulfilled promptly, even if our preference may have changed,  Numbers Ch. 30, vs. 2, Proverbs Ch. 20, vs. 25.
There is nothing in Scripture to indicate that a vow made in good faith, but later discovered to be wrong or sinful, is still to be fulfilled. 
To refrain from making a vow is not sinful, Deuteronomy Ch. 23, vs. 22.
In the Old Testament certain restriction were in place to prevent the misuse of vows.  The vows of children required the consent of their parents, and the vows of wives required the consent of their husbands, but the vows of widows and divorced women were binding upon them.  Numbers Ch. 30, vss. 3 to 13.


Consider the example of these people who made vows in Scripture:
Jephthah, in Judges Ch. 11. vs.30-1,
Hannah, in Samuel Ch. 1, vs. 11,
David, in Psalm 132, vs. 2-5,
Paul, in Acts Ch. 18, vs. 18,
The Jews sponsored by Paul, in Acts Ch. 21, vs. 23-6.


If vows are so serious, why do people make them?