''Much of people's creative ideas can be turned later into successful businesses.''
Hi, Ahmed.A.A and Ahmed_btm,
I think that noun phrase can be used to express "much of what people's creative ideas consist of," or "much of what people's creative ideas express," rather than to refer to those ideas as individual elements.
We can find a few examples on the Internet:
- Further, it was clear that much of people's ideas about brain surgery derived from material they had encountered in television or films (The brain in society: Public engagement with neuroscience, by Cliodhna O'Connor)
- Ruth says ‘It is always a challenge for us to create dance that is real to life and relevant—so much of people’s ideas about dance comes from the media or from free worship...' (Source: https://www.theology.ox.ac.uk/file/330561)
Unfortunately, many of the examples I found incorrectly combine "much of people's ideas," which is singular, with a plural verb.