I believe this is a very common way of thinking. It could be due to economics, or work ethic, or cultural / religious expectations… it’s difficult to say. Sometimes, when families cannot afford to educate all of their children to a high standard, they will focus on the oldest boy thinking that he may get a good job / good income, and help with the others. Girls can be married off to high earning men but boys are less likely to have this option.
Work ethic could also be involved: if people see work as an unpleasant, mercenary activity, then then they may regard girls / women who can escape this to have a comfortable life with a high earning man as a possibly happy outcome. In the Arab world, a lot of families push their boys into medicine or engineering irregardless of their interests or abilities… simply because these are high status, high earning professions that also grant their members reasonable mobility.