I know that I can achieve anything I put my mind to. I feel like I can shoot lightning from my hands and I wield 2 lightsabres.

However, as a primarily computational and business-oriented founder, I am trying to disrupt an industry that is dominated by scientific PhDs and institute spinouts. So even if my science is really novel, I'm still an outsider.

I'd imagine that most founders are, to an extent, outsiders. You kind of have to be in order to develop a radically new thing. You have to be dissimilar to the status quo.

"I can accomplish anything, but I won't be really worthy until I accomplish that next big thing."

Rinse and repeat after every significant accomplishment.

Not a founder (yet) but I think it's relatable. I believe in myself that I can learn and achieve anything and be really good at it but when I see the seniors and people doing amazing things, I feel like I still have a long way to go and prove myself.

I don't see a contradiction. Self belief means you believe that you can accomplish what you set out to so are willing to bet on yourself and take risks. Feeling like an imposter is a motivational drive from the other end of the spectrum pushing you to continuously improve, holding yourself to a progressively higher standards, and never resting on your laurels.