I was in undergrad 20 years ago, so my experience-basis is old. I was at a top-rated engineering school, and I had no intention of staying for anything more than 4 years.
I worked my butt off in high school, I applied to >30 scholarships as a high school senior, and I got nearly 50% of what I applied for (enough to cover my first year of tuition and living at school). The summer after senior year, I had an internship at the local military base, and I had a grocery store job at night. I saved as much as I could.
My parents made it clear that they'd give me nothing to help me with college. When I got to school, I immediately worked to become an in-state resident, and I also worked with the financial aid office to make sure that I was considered independent from my parents. This made it so my ~$5000 annual income from summer work was the only income reported on my financial aid application. I was well below poverty, and the govt and university rained money and loan offers onto me.
It also happened that my university had a really, really good financial aid program.
As an engineering freshman, I applied to ~80 potential summer internship opportunities (it was more rare in those days). That led to 2 interviews, and one offer. So I was paid >2X minimum wage that summer, and I also worked a grocery store at night. I saved as much as I could.
While in school, I lived as inexpensively as possible. I was poor, but I wasn't starving or hungry, and I wasn't eating ramen unless I wanted to. I did cook on an electric skillet or microwave to save the expense of eating out. Having a cheap pizza or McDonald's or a soda was a rare (monthly?) treat.
I worked my butt off in school, and it was academically tough for me. I certainly had no time to work a 20 hour part-time job during the school year. I worked internships every summer, and the money was decent. Between that and financial aid and living cheap, it was manageable. I got out in 4 years, I did well, I went on to grad school (free for engineers plus a stipend). Typical of ATOT, I walked into a six-figure salary right out of school.
I had taken ~$18k in loans (most of which I had invested in the stock market while in grad school). I paid it back in less than 8 years at a 2.25% consolidated interest rate.
Plan ahead. Make good choices. It's clearly doable. At least it was...