It's also disrespectful for you to assume that I will only want to do BigLaw after being in law school for a couple of years. You don't know me, my ideals, or my passions. And not everyone at a T14 is going to want to do environmental work. I really don't understand what you're trying to prove here."
I doubt the poster meant any disrespect by pointing out a truth, which is that the vast majority of prospective law students who express the same convictions as you (including people with fairly heavy experiences in the PI world, like Peace Corp alums) will start out law school thinking one thing and end up changing their views by the end of it. It's one of the major criticisms of the U.S. legal education model, and something that's systemic in how the schools recruit and train new lawyers. Holding out those six-figure salaries with large law firms as the dream job is how so many schools have been able to raise tuition beyond what should be required of someone who genuinely wants to do public defender work or represent the indigent poor. Many people argue that law school operates as a sort of trap, where otherwise PI-minded people with enormous potential and a genuine desire to contribute end up competing with their more practical, business-oriented colleagues for the same limited number of jobs. I would assume that most of us who have been through it have seen that happen, particularly if we go back to those early days and recall conversations we had with our new classmates. Ultimately even most of the people who snag biglaw will move onto something else in a few years... some of them will have the chance to return to whatever they originally wanted to do. But most will have become accustomed to the new standard of living, particularly those who have started families and/or adopted very aggressive debt repayment plans. It could literally be decades before they find a way back to the sort of work they would have once labeled their dream job.
I wonder if any schools have advice for people like the OP who may want to safeguard themselves against the groupthink that goes on in law school, without becoming a social pariah of sorts (e.g. still being able to contribute to their community and enjoy their time in law school)? Some thoughts:
-seek out like-minded individuals at your school and work together. support each other as best you can during the job search, which can get crazy once you realize there really are no jobs out there.
-join interdisciplinary associations where the people you're working with are outside the law school. it can help you retain some perspective and perhaps teach you some things you can't find in school.
-be very frank about discussing (repeatedly, without becoming that annoying hippie) your career aims and goals with friends, career services people, and profs. this will help cement your intent within the community and increase the chances people will help you in the search. otherwise they will assume you don't have any serious passions and are therefore suitable for being pressured into firm work if you have the grades for it. (I still remember walking into the career services office 1L year, informing my new advisor that I was looking at public interest NGOs in NY, DC or abroad, and having her tell me with a straight face that firms in Birmingham were hiring and I should look at their practice areas and find the ones I'm interested in. The mentality really, truly is that pervasive, even at the best schools.)
-seek out mentors who do the type of work you think you want to do and lean on them as much as they're willing. your confidence in your chosen career path is going to be shaken up quite a bit during the first year or two of law school; staying engaged with people who have already cleared the way for you can help.
-learn to accept that even close friends are going to approach law school in an entirely different way than you, and that a diversity of goals is the best way to prepare you for entering the legal profession. it will help you keep some perspective on things and prevent you from demonizing people who genuinely just want job security, a way to provide for their families, and the same level of comfort and mobility their parents had. if you don't do this you risk becoming an insufferable a-hole. at worst you set yourself up for a strong sense of failure if the right doors don't open up for you and you end up going the same way as them in the end.
I guess a lot of that was just about finding ways to keep your perspective. So yeah, just do that.