How do you feel about GitHub?

Trying to return to work for me is a big thing at the moment, because I don't have much proof or commercial working experience, i'm being told to load stuff onto GitHub. The more I do this, i'm becoming hesitant.

Insecurity? I don't know - I'm building something at the moment which is going to be a big project but i'm hesitant to upload to GitHub because I don't want my idea or code being stolen despite the "available software licenses"

GitHub is owned by Microsoft and even though everything is opensource as well as with accreditation, what truly stops that person taking your code, coping and pasting it?

Even though I support the open-source community and would help if needed, but I just think if i'm going to put the hours into a big scale project, the last place i'm going to want to put it is on GitHub as well as fear or competitors.

I'm going into Application Development and I just happened to see the Snowden movie this year and the story about what happened to his application. As a junior full stack and unicorn (apparently), it just made me want to be sick at the thought that someone could do that.

(sorry just to clarify at what happens to snow-dens application, he develops an application for a specific use and then months or years later he finds out the organisation has re-developed his application completely for a different use, and what makes it worse is that he didn't know).

Let me hear your thoughts on this one as I wonder if sometimes as much as a combined effort is brilliant, is it not a fishing pool for quick access for big corps thinking they can steal code or an idea?

Zara (Clothing) is known to do this from etsy.com