The life of relative comfort of the average HNer (engineer, likely six figure income, little fear of unemployment) is basically what the middle class was 40-50 years ago (adjusted for inflation, etc). This level of material security used to be common, even expected.
At one time it was possible to own a home, several cars and raise multiple children on a single, average income!
However, because it's getting so uncommon now, it's becoming significantly easier to save up large quantities of money for those people who are fortunate enough to have good jobs.
Think of it this way: you probably have friends, neighbors, or classmates that manage to survive on a grad student or service worker salary (~$20-30K). It may not be comfortable, but they can do it. If they can do it, why can't you? Are you too good for their lifestyle?
Now if you're making $80K after tax and they're making $20K and you're living the same lifestyle, you put away $60K/year. For every year you've worked, you've saved up for three. There's your startup capital.
At one time it was possible to own a home, several cars and raise multiple children on a single, average income!