Dear Kaushik,

Most of the ted talk speakers speak their experiences. Hence, you find them very confident since experience brings authenticity.

Watch the TED TALK of ‘Mumbai Dabbawala’. He is very confident though he doesn’t have a good command of English.

Keep in mind, people want to listen to your unique story or experience. Their could be little flaw in your speech.

On the contrary, you may perfect your speaking skills without relevant experience or authenticity. You will fail to impress yourself, not to speak of other people.

Having said that, once you have authenticity, you can practice English speaking day in day out to become fluent at speaking.

With thanks,

Yogesh