Tommy, first off, you're not dumb! You conquered the LSAT, and I'm sure you did awesome!
Also, I'm sorry about your situation
You should definitely explain that you will 100% be more successful with an MBA and/or masters from a great school than from a law school below your goals. Some people gave really good advice to me/Shak earlier about how it's important to go for what will be best for you, even if that's not immediately evident to your parents. With the law school, that's abundantly clear - the results simply are not good if you do not go to a top school, or at least to a good regional with a ton of money. Have you tried showing them articles about that? I've found that oftentimes my parents don't really believe what I'm saying until I show them someone else has said the same thing (although fortunately, they're fully aware of the importance of going to a top school and have been very sympathetic/supportive in my LSAT studying/struggles). The uncertainty truly is a big hurdle. It's not even the fun kind of uncertainty...it's so exhausting and frustrating.
ETA: I absolutely HATE when parents compare you to others, especially when if I do the same, to show that I'm not completely crazy in whatever we're arguing about, they say "That's their situation. Not yours." But then, when it comes to comparing me to others in aspects that are convenient for them, it's totally fine.