Thinking doesn't mean finding the theory of everything. It can be as simple as taking a walk and see what people who have money are currently doing that you could do for them.
Cleaning lawns, walking their dog (scales wonderfully, as you can walk with more than one dog at a time), buying their groceries for them (easily worth it, as you would only buy exactly what was on the list and not 'hey this is cheap') and it scales reasonably.
That list is by no means exhaustive, btw. Just of the top of my head.
None of these can be done by robots anytime soon, none of these require a high school education.
Yes I have some idea of how though this is -- my granddad started working as unskilled labor at age 14, and he raised both him and my grandmother from homeless near orphans to living in a (small) house with a car and in the process raising two kids to have families of their own.