There are contexts (say, the comments section of a story on foreclosure) where "I don't buy a house I can't afford" would be a full-on raging asshole thing to say. But you went further than that:

"I also don't understand how people chose to have a full-time job...AND kids"

You clearly implied that holding any full time job and having kids was irresponsible. Because "I don't understand how [something about mores]" is a construction that American English speakers use to point out things they consider irrational, dumb or otherwise undesirable. You even anticipated that your comment would make people mad ("before you reach for the downvote button", "not judging anyone"). Because you went a good sight further than "I don't buy a house I can't afford." I think my initial judgment of "naive and/or jerkish" stands.