Maybe they are right. Maybe you really can’t make that business a success. And maybe you won’t be a successful artist/musician/director.
Maybe your innovation won’t be used by anyone. Maybe the website you launch will get no hits. Maybe you won’t find the love of your life. Maybe you won’t get the job you are going for. Maybe you won’t get accepted to the university you applied for. Maybe no one will laugh at your joke at the big speech you have been asked to give.
Or maybe your innovation will change the world. Maybe your site will be bigger than facebook. Maybe you will find the person of your dreams to live the rest of your life with. Maybe you will have companies begging you to join them. Maybe the crowd will love your speech. Maybe your book will become more popular than Harry Potter.
Your life is a collection of “maybes”. Until you go out and make it happen, you don’t know which side of the maybe you will end up on.
The only certainty is that unless you go do something, you will definitely not get there.