College is expensive due to all the costs it takes to run a college and to provide the education to the college student.
The person going to college is likely going to college to study about something to get qualified to get into a high paying career such as you mention nursing.
Nursing is a pretty good paying job so they take advantage of that knowing that you're gonna be paid good for the job you want to pursue so they want to charge you enough to make it worth the colleges time to educate you in that field.
Another reason for college being so expensive is the supply and demand aspect of it.
Since college is becoming more popular with many more people wanting to go to college to get a higher paying job then the college becomes more valuable so they know that they can charge more for the college tuition since it's more in demand and people are willing to pay a high price for that college education.
If you're still in High School you might be able to get a college grant or even if you're out of school you might try looking into getting Financial aid for college.
Sometimes you may even just have to take out a personal loan to get into college.