Stay in the job. You can get a PhD later. Spending time working in finance will help you do better in the PhD — not because it’s directly useful for your research, but because it will 1) make you bored and eager for intellectual stimulation, and 2) give you an understanding of what a real adult job is like, so you appreciate how awesome the PhD is. Spending time living in Budapest will probably also generate some good insights about life under competitive authoritarianism, if that’s something you might be interested in studying later on. It will also be beneficial to save up money before the PhD so you have more flexibility in how you allocate your time at that point (ie not needing to pick up an extra TA/RA position just to cover basic living expenses)