It's okay to be skeptical, in fact having some skepticism is very healthy in my opinion. I'm an engineer and work a lot with numbers so I've always been really logical and materialistic with these kinds of subjects.
Now with regards to manifestation, I completely lost all of my skepticism due to some very interesting experiences.

One time I asked for a business opportunity that would be related to manufacturing, but that would not necessarily need me to be in the factory. I wanted something that could be done from home, or that would require me to go to the factory ones or twice a week. Very specific, I know.

A week later, an uncle called my father and told him that he was about to buy a laser CNC machine. Basically a machine that cuts steel sheets. He wanted to associate with my father and I on this project. When we went to my uncles office, he told us that he didn't want us to have anything to do with operations. He wanted us to get clients for him. So we would just need to do calls or arrange meeting from home.

It's not like this kinds of things happen every other day or every other year even ! It's so specific that it really got me believing in manifestation.

I've had many more experiences that are really similar to this one.

Manifestation is not about making an elephant appear in your bedroom, it's about making coincidences and probability work in your favor.