Oh gee, I hadn't thought of that. I'll go tell the African children. /s
Just eyeballing the life stories I know, and looking at the actual statistics on social mobility, if you do everything right you can expect to climb up like a single rung of the socioeconomic ladder. On average. There's a great deal of luck involved there, even, and it's possible to do everything right and go down the ladder if, for example, something unexpected cripples you.
Despite declining social mobility, mke_geek makes a fair point, being born poor isn't absolutely guaranteed to mean that you won't be able to have a meaningful or fullfilling life. I'm sure that many people who are born in remote villages with a subsistence lifestyle, that we would view as living in poverty, are happier than many people who are born in "first world" countries.
Anyway, OP is asking about choices, not situations that are inflicted upon them.