Other way to put it: he likes his job, so he hasnt thought too much about doing something else with his time. If he would quit, he probably wouldnt be sitting at home all day but would end up doing something - however he hasnt thought much about it since he is content with the current situation, therefore "sitting at home all day" is just easy way to put it.

I dont think there is nothing wrong in staying at a job if you like it, even if you dont need it financially.