I know you won't accept this. But I want to say it anyway, on the off chance that it lights some light bulb in your brain.
Not seeing a difference between Democrat and Republican is a privilege. It means that you are equally affected by both of their policies. Not everyone has that luxury.
If you could spend just 5 minutes considering those who are negatively impacted more by one of those parties, it should hopefully be clear that not voting hurts those people.