If you want pizza for breakfast or, if you are on vacation, and don't have to work or drive then also have a cocktail or beer to go with it. I remember, a number of years ago, when we vacationed in Hawaii with my tavern owner brother, that we were drinking Bloody Mary's at 5:00 a.m.. It was a great time but something I wouldn't do on a regular basis.
My wife works off hours and usually isn't home before 12:30 a.m.. She doesn't go right to sleep and is usually awake until 2 or 3 a.m. and sometimes 4 or 4:30 a.m.. There are people we know that think it is TERRIBLE that she would still be in bed at 10 or 11 a.m.. When most people comment I politely ask them if they get home from work at 5:00 p.m. and go directly to bed? Almost all say no and understand. Then there have been a few, especially the ones who have to call around 7:30 or 8:00 a.m., that I have to be less "tactful" with. There was one "friend?" who I basically told off and doesn't call anymore.
It's her loss.
So: If it fits your lifestyle and doesn't hurt anyone else then go for it. That's my philosophy.