the letter y is used as a vowel far more often in English than as a consonant. The distinction between a vowel and a consonant isn't the actual letter in use but the phoneme that underlies it. the y sound in year is consonantal so the y is a consonant but in sky, dry, fly, try, etc. it is a vowel sound so y is a vowel in those words not a consonant. W gets to be a vowel too, at least for Welsh words.
Are you saying "why" is the only english word without a vowel?.... oh MY you clearly haven't read "The SKY is falling" I hope you are getting my DRY sense of humour. Oh to be a FLY on your wall... c'mon give it a TRY, you must be able to find more than just WHY....