There is no value in labor as such. Value of a labor input is derived from the value of labor's output as priced on the open market. Do you think an entrepreneur who buys a property, sets up a business, buys all the capital to build a production line, starts paying employees before a single unit comes off that production line, let alone gets sold on the market--you're implying that's not a "contribution." He has taken on the vast majority of the risk, which is what earns him the right to take home the majority of the profit--and yet all this happens while paying his employees a fair (because agreed-upon) wage. Without the profit incentive, there is no investment, there is no development, there is no innovation--there are no entrepreneurs.