I feel much more confident as a musician now as I have many years of experience and training under my belt. Although I was pretty sure of myself when I was younger but now, I actually know more stuff.
I think many performers improve with age too. Maybe it is because they have so much experience they feel they don't have to prove anything and can relax and enjoy performing. I however, feel that they mellow and even their voices gain a soulful sound.
I think these next two videos give an interesting comparison of Billy Joel in early days 1978 and later in 2006 almost 30 years later. What do you think?