If you became a criminal defence lawyer, I can tell you that most of your clients would be ones who have committed crimes.
The idea behind wanting to be a criminal defense lawyer is not necessary to “protect innocent people” but rather to protect against unfair and excessive punishment against an entity that has huge resources to fuck up people’s lives for minor crimes. Like smoking weed? 40 years. (There was an article about it) Getting an abortion? Get charged with murder. Laws are just so unnecessary cruel, which is why I always wanted to be a laywer. Unfortunately I think that’s a bit too much for me to handle.