Why do we have to capitalize "I" but not "you" ?

Answer 1

Because I am more important than you.

May or may not be the right answer I just thought it was funny

Answer 2

To make it distinct and to avoid misreading handwritten manuscripts:

The Barnhart Dictionary of Etymology (Wilson, 1988, ISBN
0-8242-0745-9) says: "~I~ _pron._ 1137 _i;_ later _I_ (about 1250, in _The Story of Genesis and Exodus_); developed from the unstressed form of Old English (about 725) _ic_ singular pronoun of the first person (nominative case). Modern and Middle English _I_ developed from earlier _i_ in the stressed position. _I_ came to be written with a capital letter thereby making it a distinct word and avoiding misreading handwritten manuscripts. In the northern and midland dialects of England the capitalized form _I_ appeared about 1250.

In the south of England, where Old English _ic_ early shifted in
pronunciation to _ich_ (by palatalization), the form _I_ did not
become established until the 1700's (although it appears
sporadically before that time)."

Answer 3

because of conventions. grammarians in the past agreed to it and so it was carried on until today. but i guess the reason is because letter I is so small when written in lowercase you would miss it if not capitalized.

Answer 4

Because I can be considered a pronoun...