The only no-class commercial flights that operate today are the budget carriers, and they have the least comfortable offerings amongst all of the airlines.
Half the time I board a flight most of the first class is empty or non-existent, business is usually somewhat vacant and then there is literally hundreds of people paying $1500 for their ticket.
If you do the math, the vast majority of the flight is paid for by economy.
Economy (excluding Premium Economy) is the least profitable for the space.
The way RyanAir operates is with dark patterns. They have very strict luggage rules. Everything is optional. Their booking has ambiguous wording, causing less-savvy flyers to purchase options they don’t need. They sell RyanAir lottery tickets (!) on flights.
It’s like playing a game that is solely fueled by cosmetic microtransactions. If you can/know to not give in to the various trappings, you get to play a good game for free. Except in this case the game is air travel and the win condition is extremely cheap airfare :)
They’re no different from a lot of other budget airlines. The seat pitch is as low as it can go, the seats are cheap and uncomfortable regardless of pitch, and everything other than the seat is a paid extra.
I had to take a reasonably long Air Asia flight last year, and the worst part about it was they woke you up every two hours by turning all the lights on and making a very long announcement that the duty free cart was going to spend the next hour trying to sell liquor and terrible perfume to every passenger.
However on that same flight, one of the paid options was for an incredibly cheap add on that gave you priority checkin, priority boarding, priority immigration, and priority baggage. It was like $10 or something, insanely good value.
Non-budget carriers provide are more reliable and they provide food service and arguably better seating and entertainment.
I fly economy on a "premium" carrier all the time, and it's a much better experience but if I crunch the numbers, I fail to see how first class has much to do with the flight going ahead or not.