It's the things some/many of us have been suggesting for a long time. Things like: Use a community college if possible, don't waste your time finishing an undergrad degree (four years of tuition when three will do), live cheaply, go to your IS or a cheap OOS school, take the time to apply for scholarships every year (even $500 brings you a huge ROI), etc. Not everyone promotes all those things (except, maybe, me), but most of us support some portion of them.
This is tough to say because there are people here who went this route, and I don't want to beat anyone up or make anyone feel bad. And they are or will be just as good of a vet as anyone else. And they will find some way to make it work, probably. But I would think very, very, very, very hard before heading off to some route where you're going to end up $250k in debt. That's just too much. Seriously, for those people who are in that boat, not trying to make you feel bad. I just would advise anyone heading that way to do anything possible to avoid it.
And as someone in this boat, don't feel bad. You are 100% correct. I beat myself up for it at times, I was naive. I think a big part of it is that I am the first in my family to go through college and professional school. Nobody in my family had really dealt with all of the loans and things before so it was a serious winging it sort of deal.
Basically everything LIS stated above. Go to a CC for as many courses as you can. Better if you can work and pay for those courses yourself without impacting your grades. Live cheaply. Just because you can get $20,000 in loans in undergrad, does not mean that you should. With federal loans, you can always decline some and get more later if you need (or you should be able to, speak with your financial aid office to be sure).
Go to an IS school. Don't have one? It would be cheaper to move and take the year to establish residency than it would be to spend 4 years in OOS tuition. Yes, being IS does not guarantee an acceptance, but it does give you better chances (depending on your GPA/GRE/etc. I was told point blank that if I had been IS instead of OOS, I would have been accepted at some schools instead of rejected/waitlisted). So, get IS tuition if you can possibly do so.
Scholarships are great, check with your school to see what scholarships, if any, they offer. It might not seem like a lot to get $500 or $1000, but once you figure interest on top of that, it really does help. Also, scholarships in undergrad... there are a MILLION of them, seriously. Look. I wish I had spent more time looking and applying for them. You can make it out of undergrad off scholarships, if you apply to enough of them. We will put this the way my mom told me but I ignored her, say you spend an hour to write an essay for one scholarship that is worth $1,000 and you get it. That means you just made $1,000/hour (and more because interest). Seriously, put the time in, it will be worth it later.
Live with roommates. I know, I don't like it much either and I have been living alone for a while now, but even just one roommate can cut your rent/utility expenses each month in half. Meaning you can save around $250-400 per MONTH by simply living with someone. Add that up over a year, then add that up over 4 years. Yeah, it is worth it, even if you absolutely hate people, you will survive for 4 years living with someone else.