Here's another way. As the worker, already working full-time, maybe you have better things to do with your life than working harder. Furthermore, the worker is probably thinking:
"If they want me to work more hours, why not pay me for more hours, including time-and-a-half overtime, per the law? Why offer a profit-share? Answer, mostly likely because the profit-share costs them less, and therefore, pays me less".
In that light, unless the factory management can explain how the extra hours they want people to work is likely to work out better for them then just getting paid for more hours, why should they accept?
* you do lots of work now, up front
* you have no say in the business
* you have no say in the investment returns, for example, if profits are made, management can just give themselves higher salaries that come straight out of your share of returns
* your investment isn't portable or recoupable, if you leave it's nothing
* if management is bad, it's also nothing
* you're skeptical of current management
Should you invest your time in this business?
I think it just puts a voice to what a lot of people think, but never say.
[edit] Sorry, to add details, they were trying to increase throughput with the same number of workers. The factory already went 24/7 under EU guidelines, so more hours were out of the question.