In 2014, I posted my car purchase on FB.
It was a 2003 Pontiac Vibe with 165K miles for $2,500. Most of the comments were negative. My favorite was, "Why the hell would you buy a Pontiac Vibe?" I saw that person at a wedding last year and they pretty much complained of money problems the whole time. However, according to him it's his ex-wife's fault, not his fault.
For those of you who don't know much about the Vibe, it's the same car as the Toyota Matrix. It was a joint venture between Pontiac and Toyota. It has a Toyota engine. I drove it for 5 years and 57K miles before it died. Very minimal maintenance.
I don't like to shit on people's parade. Let them enjoy their life. Once they start complaining about their life and ask for advice, then you can contribute. If someone is in relatively good shape and posts on facebook about eating chocolate lava cake for dessert, don't comment about how that food is bad for you. However, if that person comes to you, 100 pounds overweight and asks for advice, then give it.