You called them poor and you still criticize them for not investing? I don't know what the word "poor" means in your own perspective but going by general definition of poor, you can not expect such people who hardly feed and shelter for themselves to take a risk in investment. You can not risk like them if you don't earn like them.
I know many poor people who know how to invest and make their living better by investing and saving.
In Fact some people - - like me dont know how to invest and when they do - it is a mess.