Everyone has doubts.

It’s human.

If you had no doubts there’s something wrong with you.

The trick is to keep them to yourself.

Not everyone has all the information you have, and so cannot allay their doubts with counter-arguments.

You showing doubt sows the seeds of panic in your staff/partners/shareholders.

That is a guaranteed way to bring your premonitions of dread to fruition.

Keep your doubts to yourself.