Not me, but my business partner:
About 13 years ago his daughter and last remaining child living in the house was finishing up medical tech school and was planning on moving out.
In anticipation of not having tuition or a child in the house to pay for, he started work on his dream man cave. He tore down the old garage and rebuilt it and redid all of the drive with some pretty cool hard scape work. Inside he had a kitchen, bath, and open area where he put his new pool table. All surfaces were hard and could be washed down with a hose if need be. It even had floor drains. The fridge was stocked with plenty of beer and nothing else. Antlers and other hangings not suitable for the house were placed about the room and got it just like he wanted. He even beat cancer during this time. Life was good.
Well, the daughter did not move out, so while she was living there no crazy parties were allowed.
Eventually, daughter met someone and he had to fork over a bunch of money for the wedding. Like 30 grand or something. But it would be worth it he thought, just so she could be out on her own with her husband making their way in the world.
Unbeknownst to him, his wife promised them they could live at home to save money.
So the man cave had to be converted to a residence. All new flooring, new kitchen, new bath, new bedroom walls, closet walls, and lighting. Pool table had to go to storage along with all of the other trappings.
He thought it would be ok after a few years when they moved out after saving some money for a house.
Well, that day never came because his daughter freaked out and got a divorce 6 months after getting married. So daughter moves back into the house and garage apartment sits empty.
So after about a year when the coast is clear, business partner converts garage apartment back into a man cave. Walls are torn down, new flooring, new kitchen, new bath Yada Yada yada. All the while, daughter is still living at home.
He has been enjoying his man cave for a few years now worry free. His daughter even met another guy a few years back and he has a good job so her days at home are numbered.
So last week on Thursday, he doesn't show up for our usual beer drinking meeting even though he says he would be coming right over (he basically lives across the street from our office/yard).
So I walk on over to see what's up and he and his wife are under the man cave patio-talking. I can tell I am interrupting, so say my hellos and leave.
The next day I apologize for interrupting and he just shakes his head. He says his wife told him that his daughter wants to buy a house and move out and wants to move in with her boyfriend to save money. He asked where they were moving and his wife tells him, she said it would be ok if they moved into the man cave, after it was converted back into an apartment. Face palm.