Buying a 2016 Mercedes S550

I'm in the market for an S550 and I found a posting that came up for just about $9,800 for a 2016. It has a clean carfax and title with only 2 owners, although it has 144,000 miles. While I know that the mileage alone is a big redflag, just based on the market in my area these cars are averaging about $19,000, which makes me wonder what else could be the culprit for such a low price. If anyone has an opinion on what to be mindful or conscious of or really just an explanation, that would be much appreciated!

Note: I plan to do my own maintenance, and I am expecting higher maintenance costs. Please don't try to persuade me out of buying an older S550.