value is generated using both capital from the already rich, and labour from the poor.
Over time, labour isn't increasing in productivity. It's capital that's increasing productivity, such as by improving labour's efficiency.
With this in mind, why is it that the rich shouldnt be the ones to capture the new/increased productivity? After all, it is their investment that would make such productivity possible. If you had told the rich that their investments would not actually gain them profit (because labour captured the increases that produces the profit), they would not have invested in the first place.
One way to break out of this cycle is for labour to provide something more than unskilled labour and merely using capital to produce goods/services. For example, research and development, knowledge/skill from education, etc.