Hate to admit it, but I was that a**hole once. Went to Portugal during a lull in the pandemic. Booked business Cass for myself, wife, and 7 yo daughter. We thought that our 2 yo would just sleep on either of us considering it was (a) late, (b) it was a 7 hour direct flight, and (c) our older daughter was an excellent traveler from a young age.
Well, apparently all children are different. The 2 yo was a feral creature that was unable to sleep, get comfortable or eat. It was an awful experience for the cabin and I felt absolutely terrible. I finally understood infanticide.
Anyway, not trying that again in the near future. Maybe in late 2023, but not before then.