I think thats for the following reasons. Because the c manager understands the value of investment long term and they believe they can impact the company in a positive way. They also likely have more disposable income.

A factory line worker has very little control over the performance of the company. He wants his weekly pay to be in full cash and that's it because he either has less disposable income or doesnt understand the value of investment.

If the line worker wants to invest he would likely invest in another company than his own unless his company was preforming exceptionally well.