You can, and should, keep your eye on your backlinks. Monitor your webmaster tools and track your rankings. If and when someone starts a NSEO campaign, you need to get busy and use the disavow tool. If the attack is fairly bad, you can hire a helper. Some Fiverr gigs pop up to help with this, and/or you can hire a virtual assistant to combat the offensive links.
NSEO attacks are usually not as effective as you might think, especially when you have tiered links. The tier system pumps up the juice, and often negates NSEO attempts, unless your competitor has a real ax to grind. If you run into a real problem, you should seek out a professional to help you.
It's not futile to fight back. In point of fact, many of the most profitable websites have to deal with this, and unfortunately, it's part of the cost of doing business online today.