No one else needs to believe in you. The only person that has to have the absolute conviction is You!
The world will doubt you. It will overlook, ignore and underestimate you. It may judge you a fake, a con artist, pretender, manipulator, contriving. The world will do what it will.
However, all that is going to matter is what do you believe about You? If you have the belief, the conviction that is unshakeable, the whole world will gradually but surely fall in line to match your belief because you will give them no other option. And if they don’t, it does not matter because their belief will not matter to you.
All that will matter is your belief and conviction in You – no one else but You!