"Your own life matters most" - In what sense? More than that of others?You know what? This is a sloppy formulation. But see the point immediately below, because I think it deals with most of the trouble you're having with what I'm saying.
"What's good for you does not come at the expense of other people." - Do you have evidence for this? Does stealing, which might in some moment be good for a person, not come at the expense of another?
Was stealing good for Bernie Madoff? Look at the evidence. He ended up in jail, penniless, and what's left of his family will not speak to him. His son committed suicide. Even before he was caught, his life was a living hell - he admitted as much in an interview.
"How can you make your mark on the world" - Doesn't this presuppose that 'making a mark in the world' is a more 'important' cause than changing diapers?
Things are important or unimportant only in relation to particular lives, and everyone has unique, specific goals. For example, if my goal is to become a world-class concert pianist, fathering children before I was thirty would definitely make the more important (again, to me) goal impossible to achieve.
"If the ideas people held were simply a matter of economic conditions, no one would ever rise out of poverty." - Id be interested to see some statistics of the frequency with which people escape poverty. I have a feeling the numbers are fairly low.
Statistics are only useful when you are ignorant of a specific phenomenon, and have no way to make the necessary observations yourself. What matters is specific, actual people, not some aggregate average that describes nothing in particular and no one specifically.
The fact that some people rise from poverty is all that is needed to prove that it is possible.
One last point occurred to me. People rose out of incredible poverty en masse over the last 150 years, following the industrial revolution. in the 1860s, even the wealthiest businessman could not fly across the country in a few hours, call people around the world, get treatment for serious illnesses (e.g., valve replacement heart surgery), use computers, etc. A lot of people look at poverty from the perspective of relative differences, but I'm just happy to be alive in a time and in a place where there is so much available, in absolute terms (because that's the thing that actually makes a difference in my standard of living).