Most lawyers earn around $50,000/year. $70,000/year seems like a lot of money, I'm sure, but consider that the majority of people who go to law school end up in debt over $150,000, and often over $200,000. To pay back that sort of debt in a reasonable time frame, you need a job that pays more than $50,000 a year. Otherwise, you'll be forced to extend the payments over 20-25 years. That means paying more interest over the life of the loan. And if you ever plan on buying a home, you'll have great difficulty with that much law school debt.
Starting your own firm is very hard for several reasons. 1 - You need a reputation in the community and a client base that you can bring with you. That's why most people don't go into practice for themselves right out of law school. They have no experience, no clients, and usually don't have a lot of money. Most lawyers try to work for someone else for a number of years to learn the job, but also to make a dent in their student loan payments. 2 - You won't turn a profit for a while and you'll need to pay rent, taxes, and salaries for your employees. That means you'll need to have quite a bit in savings before you even begin.
Although law school is a long way off and you're getting ahead of yourself, you should keep this information in mind as you attend college.
-Law school admissions are based almost entirely on your college GPA and your LSAT score. Pick a major that's going to help you maintain a high GPA. When you begin studying for the LSAT, treat that test like a full-time job. Take as many practice tests as you can and read the PowerScore bibles (LSAT prep books). Dedicate at least three months.
-Your best chance of securing a job out of law school, let alone a high-paying job, is going to a top law school. What are the top law schools? Refer to the US News and World Report guide. They're known as the "top 14": Yale through Georgetown. For the most part, these law schools place the most graduates in top firms--the kind of firms that pay $160,000/year *entry level*, not after years and years and years of working--as well as in prestigious clerkships and law school academia.
I know many children of the "FOBs" and I know that their parents put them under enormous pressure to do something impressive. In an attempt to satisfy their parents, they attend horrible law schools with basically zero job prospects. They graduate in debt with no career opportunities whatsoever. Don't do this to yourself just to make your parents happy. Unless they're willing to pay off your law school debt, you shouldn't let them make this decision for you.
Keep your grades up. Study like a maniac for the LSAT in a few years. Try to get into the best law school you can. If it's a top 14, all the better. A top law school will open up doors for you that lower-ranked law schools just won't. You'll be more likely to find work, you'll be more likely to find work that allows you to pay back your loan and live comfortably at the same time, and you'll be more likely to transition later into what you actually want to do.