Why do my parents fight and then somehow blame the fault on me?

Because they are aggressive in this moment. If you tell someone who you do like in an argument: "I wish you'd be dead" you don't meant it so, right? So it's the same with the parents. They don't meant that so.

They might do that in the heat of the moment and are not thinking straight and definitely do not mean it.

They mostly fight because of our financial issues then blaming me because my studies cost them a lot of money.

I am going to take this one by one- Why do my parents fight? There might be umpteen number of reasons right from different interest, to the fact that they are angry with themselves, to unfulfilled wishes. THe reasons could be anything. Even may be difference in opinions on whats best for you. Blaming fault on you- Parents unfortunately despite wanting to have all figured out do not have that most of the time. So when they start running out of options to say to the kids, they resolve to the age old tactics of you should have managed it differently. Your take- Take the learning leave the negativity. Well honestly this is a parent speaking. As a child or a youth dont please don't take it personally. Think of it as something that your parent are also probably doing for the first time irrespective of the fact whether or not you have an older sibling. They are learning as well. So give yourself an opportunity to learn with them.

Because you are the one 'thing' they have in common, you are both their responsibility, their joy, and concern. When things goes wrong people find things to blame, even the good things. The fact that they casted their dreams and hopes and even quarrels on you, shows an emotional investment they have on you. I have faith that you are capable of taking the reponsibility up and get them to make peace with each other and remind them that things are going to be okay because you all have each other. This would be benefit your siblings too if you have em'. Peace!