Ridiculous. 6am flights are the work of the devil. But there is no need to be at the airport for midnight for a 6am flight. 2 hours before is fine.
DH and I (and our 2 DC) had a 6.30am flight to New York about 15 years ago. Had to be at the airport for 4.30am. Airport was an hour's drive, had to allow an hour and a half in case of delays, so got the taxi at 3am. Hardly slept the night before. Went to bed at 8.30pm, didn't get to sleep till 10pm, then the alarm went off at 2am!
We were all so tired. The plane was an hour late and took off at 7.30am. At that point we had been up for 5 and a half hours, had only had 4 hours sleep, and still had a 6 hour flight to go. Got there 1.30pm - 8.30am NYC time - and were all shagged by 5pm their time (10pm ours.) We all flaked out on the bed, and were wide awake at 4am the next day!
We walked around the quiet streets of Manhattan at 6am, and took in all the sights, stopping at 8.30am for breakfast, then going into the tourist places from 9.30am. We were tired again by 8pm though. 😆 Took us 3 days to recover, then 2 days later we went home!
Will go for a 2pm flight next time. Midday at the latest. Even if it costs more. Enjoyed the trip as a whole and have nice memories of it, but will never do a 6am or 6.30am flight again... Especially not if there is more than a couple of hours time difference. It will be more tiring now, being 15 years older! As has been said, I am too old for all this shit now, and too old to miss a night's sleep.
Oh, and yes, I wouldn't get a hotel for a 6am flight.