You don't keep that surplus for youself, it's for the company profit and company profits have 3 very important functions in economy (we can talk about them also).

About the risks. If the company fails you get bankrupt, but the worker is not, they got paid as was negotiated all the way.

You as an employer need to also do work to find a suitable worker, a work that doesn't pay unless you find a worker that is willing to work for you and will succeed at the job. If the job is dangerous, you would need to pay higher wage and do more work to find a worker with suitable skills and willingness to work for you. 

The worker can always start a business and work for themselves, but there's definitely many reasons why many workers decided to work for someome else.

You have interesting way to look at this, I almost thought the same before I started studying austrian economic theory.

Do you believe that every company should be non-profit?