Is this sentence grammatically correct?

Yes, correct.

Thank for your reply.

I thought it must be "that" instead of "than"

Yes, it should be that. This is an error that occurs when I type too fast. It is also an error that is easily overlooked when asked to correct a text.

Thanks, Philip.

This is the reason given by the writer of this sentence when I asked about this mistake. Is he honest or trying to deceive me?

"it is a kind of self speculation. this method of addressing is used by a lot of public speakers to invite a friendly feeling from the crowd. grammatically it may not be by the books but yes, this sentence is always found in public speeches. "

I see no relevance of what the author says here to the original sentence.