The Dunning-Kruger effect is an extremely important psychological effect to understand, both in our own lives and in understanding other people's behavior.
The effect shows the relationship between confidence and competence:
1- When you have zero skill in a field, your confidence is naturally zero: you know you're not good at the skill
2- When you have a little bit of skill, it's easy to exaggerate your competence and assume it's better than what it naturally is. Therefore, you become over-confident beyond your actual competence level
3- With some additional experience you realize you're not as good as you thought you were, which leads to a drop in your confidence that can go below your actual competence level. In other words, you don't see how good you actually are.
4- With more exposure - and having gained real competence - your confidence level shoots back up, and your confidence is now a more realistic reflection of your competence level.
Most people are in Level 3: they're competent at what they do, but their confidence doesn't match their abilities.
They're timid and constantly sell themselves short. It's mostly because they compare themselves to real experts, and so they undermine what they know.
Instead of comparing themselves to experts, they should recognize the progress they've made from Level 1, and to acknowledge they have a lot to offer everyone that hasn't reached their level yet.
Don't sell yourself short.
You don't want to be over-confident, but you also don't want to hide your strengths and ability to serve others.
Give yourself permission to shine. You're the only one holding yourself back, which limits your opportunities to grow and serve, depriving others of what you have to offer.