When you have a single income as an employee with no dependants or spouse, your taxes are dead simple. It's when you have more things to consider that taxes get complex. If you own a small business on the side, have some kids, own a house, a wife, maybe you came into some money from an estate, also you did some contract work on 1099... That's just normal people types of complex tax stuff. If your business does well, you can expect the adage "more money, more problems" to rear its ugly head.