Playing for someone besides yourself, whether it is for 1 or 100 people is what I usually call the "missionary" part of guitar playing or any other instrument for that matter.

Many things have been written about the public performance of music (anxiety attacks, stage fright, cold hands, etc.) and I have gone through a few books dealing with the issue  hoping to read something like --"...in order to eliminate that butterfly  feeling from within yourself, you must do the following:..."--   

Take my word for it, you will never read this anywhere. 

Having played for many years, practiced constantly and having received the highest grades in college, are by no means the indicators that you are fit to play concerts. Concert playing is a special vocation within the vocation. Playing flawlessly is not what it takes and having the guts neither. The whole issue has to be examined from a different angle. Start by asking yourself:

• Why do I want to play concerts? 

1- "I played for many years and it is time for other people to see what I have been up to...",  

2- "I think people needs to know my interpretations which are simply better than the ones by other players",  

3- "I need to feel the energy flowing between the audience and me",  

4- "I won all the major competitions and I deserve to play for real people..." 

5- "I think that in a materialistic world playing music brings people closer to their spirit"........

then: remember that most hard workers are never known but discovered at best, what you think about your playing is just that, what you think, there is no energy flow in concert giving but a lot of sweat and very patient people waiting for you to finally play Recuerdos, the sure thing competitions give you, besides an over inflated ego, is a huge, ugly repertoire and the music scene is so prostituted lately, that souls will most likely be disappointed by your silly virtuosity.

• Music making is neither  about doing finger acrobatics nor a matter of who plays a piece in less time. 

I agree with you that, unfortunately, there is a lot of showing off going on by players all over (In the violin and piano world this has simply been going on for a loooong time...). The roots of this evil are sponsored by major competitions that push players to give up musicianship and embrace circus acts. Classical guitar magic, is not about speed record  breaking but an idiom which common people love because it supposedly makes art music available to everyone. Yes, just about everyone I know owns a guitar, or knows someone who does....an old 50 bucks guitar maybe, but a guitar nevertheless. 

The piano and the violin intimidate common people, the guitar does not unless you aim at doing that on purpose. The "show off" have made the road very hard for the rest of us. They may fool common people, but they sure do not fool me. I have attended MANY concerts where the audience looks around to "understand" whether they just attended a good guitar concert or not. They need "someone" to certify, maybe with the nod of their head, something....anything, because they simply UNDERSTOOD NOTHING. 

They made it all the way to the concert hall...paid the ticket and got slammed in the face by the very artist !! They waited and waited and they were never given the gift of hearing those somewhat familiar tunes (Recuerdos, Romance, Estrellita....) because, come on, the interpreter was too good to indulge in that easy stuff...he was there promoting some ugly contemporary piece.

It is easy to hide behind unknown pieces. It is easy to impress at 200 miles an hour than at 5 !!  Guitarists think that everyone has heard enough of the classics !! NOT TRUE ! If your reasoning has become so distorted that you truly believe that, it is, either because you are attending too many guitar festivals, or because you think that everyone has a Segovia or Williams recording. NOT TRUE ! The guitar repertoire does not need to be expanded. What the guitar repertoire needs is true musicians with their feet on the ground who make a great effort to make the tunes common people love "guitar playable". That is a challenge !! 

• What about the other horror of imposing pieces in competitions? Or the even worse  horror of being judged by fellow colleagues, when in the real concert scene our survival will depend on the audience and not those ridiculous judges!! ....

Imposing an age limit !! Talk about discrimination !!  It shows that the very organizers of these monstrosities do not trust the audience which, ultimately, will make the event happen. You are all making part of a dark chapter of guitar history.

All the above answers, converge in one big truth. Our ego craves to be fed. 

When your reasons start sounding more like, everything else I tried does not make me happy nor puts food on my table (usually these two truths converge in life) or, there are simply not enough players in my town, or... I want to remind my fellow human beings that the human body and brain can persevere silently for hundreds of hours in the pursuit of perfection and music brings happiness to the soul,  then you will at least sound honest or have a clear idea of what concert giving it is all about.

Ultimately, all musicians, will have to learn how to co-exist with the phisical and psicological sensations that concert giving bring along and the million dollar question --"Why did I have to book myself for this concert in the first place?" -- will always hound us in the hours or days prior to a concert.