Nothing locks you in the Fortune 500 company. Give it a try, moonlight on your business on the side. If the 9 to 5 job doesn't please you, you can leave any time you want. You might lose your first year bonus or something, but at least you gave it a try.
What I'm saying is you don't have to stay there for 7~15 years, and you can (probably) build your business on the side. As FINate mentioned, just make sure it's ok per your company's policy (it probably is as long as your side business is far enough from your company's core business).
In my case, my visa does not allow me to have 2 jobs. So instead I have a job and a hobby (which is slightly different from a tax perspective)
Personal case: I'd rather have my side gig be just a hobby that might or might not make money, rather than having my financial future depend on it. So my choice is to stick with the corporate job until I'm closer to Financial independence.