Generous
Back in his times, Steve knew poverty very well. His father died when he was an infant; living with his mother, being a sickly kid whose health consumed all the money she managed to earn – it meant eating the cheapest foods and never enough of them; meant living in one room and wearing the same clothes and being cold. Then she too died and Steve was left on his own; even with Bucky it wasn't much easier. War and death and destruction didn't feed people, didn't spoil people.
After a few months of living in 21st century, it's still hard to get used to the easiness of getting things. Now everything seems – lavish. Excessive. Steve can't make himself overlook these faults like modern people do all the time: he notices quickly that the world strives to appear particularly generous – while in reality it's everything but.
It used to be the opposite and that was honest. Honest and real: goods for work, money for work. It was fair. So Steve doesn't want anything gratuitous from S.H.I.E.L.D. or the government or Stark, he wants to earn his keep.
He's received seventy years free of charge and it's enough liberality for a lifetime.