What if they are the largest, been around for years, seem to be reputable, etc..?
A quick look at ahrefs shows that most of their ranking is for keywords that are irrelevant to their advertisers. They also tell their advertisers false numbers to increase rates.
Their backlinks are mostly circa 1999 directory sites or crappy exact match domains that also look like they are from 1999.
How do you utilize this knowledge to your advantage? (In a way that is NOT negative seo/spamming their site).