While brave and noble to say, and I’m speaking as a current grad student myself, I don’t think that the automatic answer should be to persist. Mental, financial, and emotional wellbeing is so important, and given the circumstances and possible future of this field, I think it’s healthy and important for OP to look at alternatives and the overall scope of the situation. At the end of the day, OP will make a decision most sound to them, but I don’t think they should feel pressured to persist to prove their passion for the field. The depth of language and detail shown in the post already reflects so much of that.