These two things are easily confused but are separate entities. You can be confident about a skill or a performance and do it well when required but in other areas of your life you may feel worthless or less than adequate. We see this in some high achievers who have got to the top in their field but turn into workaholics & perfectionists to prove to their detractors, imagined or real, that they 'have what it takes'. This can often lead to other problems outside of work such as family breakdowns & drink & substance abuse.
The surface confidence that can come from being good at something relies on the admiration & approval of others. This is the 'externally validating' type of personalilty. When you feel good most of the time for no apparent reason, and this could be true for someone without high status or accomplishments, then you're 'internally validating', that is, you don't need anyone else to tell you what you're worth because you already know. And this kind of personality is usually more creative and individual, eventually contributing more to society in terms of rational thinking and ideas because they don't feel constricted by what other people may think of them.
The patterns of thinking that lead to us wanting to please are buried deep. Sometimes the only way to get to them without going through years of psychoanalysis is to use a shortcut, and that shortcut is the trance state in order to 'turn down' the critical factor & enable us to make changes at a deep level. Most of the time we don't even need to know what the original issues were, or go digging around for them in the same way other therapies might. Context free therapy can be done under with the aid of a hypnotist, so that the client 'heals' themselves using the resources they already have, or be empowered to find whatever they need to make serious progress with the issue.