The pursuit of a cause of the people, can "dream" doing higher. Although at the beginning of a dream, but as long as keep doing, do not easily give up, dreams can come true.
What you'll often see is a group of undocumented immigrants doing scut work - doing sweeping up, carrying heavy stuff, setting up the machinery, working alongside either native-born or documented immigrants who are doing the higher-paid skilled work - carpenters, electricians, plumbers, that sort of thing.