I lived with my parents for a 1.5 years while I was getting my MBA. Went straight from my Bachelors to my Masters, so I was still in my early 20's.
My parents are living with me.
I'm not in my 20's though.
It's short term. They finally sold their home in Chattanooga, and it had a short closing time. They couldn't find a house in the area they want in time, nor an apartment with a very short term lease. So, they are living with us. They have an offer/purchase agreement on a house that is under construction. Originally planned to finish on July 12, but now is backed up two weeks to July 26. I knew the first date was unlikely when I saw the house a few weeks ago. Oh, it
could be done, but was unlikely to
get done by July 12.
When our oldest graduated college she was originally thinking of moving to Chicago with friends and finding a job there. That didn't pan out and she decided to move back to Atlanta and find a job. We (her mother & I and her father) asked her where she was going to live.
That set the right expectation. Her father manages apartments (typically smaller, older ones) and rental storage. He gave her a good deal on an apartment in an old building, but a very hip location. Yes, she found a job quickly and has been doing very well.
The two younger kids know we are downsizing our house, most likely in two years. They know there won't be as much room then. Oh, we'd take them in if something went sideways, but they know we won't be very forgiving of slackers. Not that we have to worry much about that, they have a pretty good competitive streak in them.