21 is not to old to become a great guitarist.
If you can hang out with the great guitarists you
could also be a great guitarist.
Most all great guitarists stole everything they could
from other great guitarists then came up with thier own
style.
You should alwasy get around guitar players that can
play better than you .This way you could be a great
guitar player by stealing and learning everything you
can from them.You can learn alot faster plus cut some
years off on getting to the top.
If you hang out with beginner guitarists your progress
is going to take alot more years to become a good guitarist.

Mark