Even the people closest to us in our lives, our parents, partners, children and friends are like closed books, to which we will never have access to their thoughts and feelings, only through a filter of their communication and the selection of things they wish to tell us. And this selection will always be partial.
Someone giving a lecture, might seem extremely relaxed and confident, but could be feeling utterly nervous on the inside. We will never know.
As a matter of fact, if the one giving a lecture is extremely good, he/she is probably very nervous on the inside. Several theories suggest that the “impostor syndrome”, worsens as people improve their abilities. As you receive more compliments and start to surround yourself with very talented people, you might begin to feel worse by the comparisons.
On the other hand, people actually having no talent at all will probably have no idea that this is not good, because they can’t distinguish good from bad (this is called the Dunning-Kruger effect).
In conclusion: If you think you aren’t sufficiently good as a writer may be a good sign.
The truth is that most of us either being novel, experienced or renowned writers have the constant feeling of improvising at all times.