1) Programs have their pick of students. You're competing against people who will smile, nod, and do whatever asked of them while dressed all preppy. Compare that to someone who look like he/she has been working all night, or someone who says, "I can't do that, I have to work that day". Program staff are going to favor the other person.
2) This isn't undergrad. Grad school is a wholly different beast. Let's look at the schedule. Say you're taking 12 hours per semester the first year, no practica. Rule of thumb is that one hour of classroom stuff creates about 2-3 hours of out of class work (e.g., reading much more than in undergrad, writing 10+ page papers several times per month, writing 10-15 page assessment reports because that's what our profession does, emails, etc.). So 12hrs of classroom +30ish hours of other school stuff= 42 hrs of work. But that work is not evenly distributed. Your professors might email you at 3pm and expect a response ASAP. You might have 3 ten page papers due on the same week, and then nothing substantial two weeks later. You might have to read 200+ pages of stuff in a few days, and then not much for a few days. And you know that mid terms and finals are not better. During the slow times, you could pull off working. During crunch time, it verges on no way. Now factor in the 99% chance that you will make a mistake in scheduling at least once. Then add in practica at 20hrs per week, and lab time of whatever. Then add in when you have to go present research to those stupid things that are not exactly conferences, but you have to wear a tie and stand next to a poster.
3) Risking work for grad school is a bad investment. You're investing approximately $150k in tuition to get to your career goals. Let's say rent is $1200/month (i.e., 14k/yr, or 72k over 5 years). This means you're risking $150k for $72k. That doesn't make any sense. If you go a bit bigger picture: You're investing a geographical move, a 6 figure tuition, a half a decade of work, your spare time, and delaying the start of your career. That's not something to be taken lightly.
4) Expensive programs are VERY risky. People do have success stories from them, but not all. Looking at Loyola, it would be approximately $176k in tuition debt alone, if one graduated in 5 years and the interest rate was 4.3%. Using a ten year repayment schedule, one would have a monthly student loan payment of about $1800/month. The (outdated) APA salary survey places modal incomes between $80-100k.
Assuming zero undergraduate debt and zero other debts including car payment, if the person made the lower end of income the MAXIMUM house they could afford would be approximately $101k. Using the higher income estimate, the maximum purchase price for a home would be approximately $200k. The median home price in the USA is around $250k. Want to put your kid in daycare, buy a new car at any point in that decade, or have some medical bills, and it gets a lot harder. Marry well, and maybe not so much.
OR you could hustle to make more than the modal incomes, refinance through places like sofi, live lean for a few years, learn about other student loan repayment options, etc.
5) That being said, I worked in grad school and during internship. The huge caveats are that I have an insane work ethic that verges on self destructive, and that I had some non-traditional opportunities from my previous career which allowed some low hour/relatively high paying consulting work. There were some challenges in shifting between the style of writings, style of dress, phone calls, emails, and (rare) travel that each setting required. I'm pretty sure my PI knew that I was doing other work in the lab, but was happy to ignore it so long as I produced.
In internship, I was allowed to do four 10 hour days. On my day off, I worked for a PP that needed psychometrician and research work. That transitioned into adding Saturdays psychometrician work at a hospital. If you look at the hours, that's ~40hrs at internship, another ~4 hours in roundtrip commute for internship, guessing ~2hrs of emails and administration work per week, ~10 hours in PP work, and ~10 hours in inpatient work if everything went according to plan. Total is 66hrs worked per week, without including internship reading, studying for the EPPP, applying for licensure, or looking for a post doc. That is when I learned that I can work 13 days in a row, but not 14 days.
