I'm reasonably happy that I'm attending law school... I didn't know that I would like it, but I got lucky.
I was thinking today about how upset I would be if I hated law school. You'll probably spend between 35,000 and 100,000 on law school (which you are constantly reminded of) but even more importantly, you'll probably spend over 5000 hours (55 hrs/wk 32 wks/yr * 3 yrs) studying/going to class over your law school career. (Some people will spend a lot more than that)
Even if you only made 10 bucks an hour at a dead end job, you could make 50,000 in that time period. So that's another 17k per year that you are missing out on.
Aside from the financial opportunity cost, think about what you could do with 5000 hours...625 8-hour days.
A talented person could probably get pretty good at guitar, learn to speak Chinese fairly well, and start their own business in that amount of time.
Law school is interesting, stimulating, and a good investment for a large percentage of graduates, but you should still think about what you're giving up.