Don’t stay in something just because you’ve already spent a lot on it. That money’s gone either way.

Money already spent cannot be rescued by spending more time. Two years into something you dislike, those two years are gone whether you stay or leave, so they are not a reason for either choice. What should decide it is the next two years.

When you catch yourself saying you have come too far to stop, ask the question fresh: if you were starting today, with what you know now, would you pick this? Write the answer somewhere you will see it. That will not settle the decision alone, but it removes the part that was never a reason.