Not at all.
Let's say coach is $1600, premium economy is $1800, and business is $4000. I'm definitely going to buy premium economy, totally worth $200 because on transatlantic flights it's a lot better than coach. (I've done this before)
But $4000 for business? I might do it for $2000.
Law of diminishing returns and all that. I'll pay 20% more for something that's 50% better, but I won't pay 200% for something that's 60% better.
Now let's look at some real prices. Say you wanted to fly from SFO to CDG in September on a nonstop flight. Economy: $710. Premium Economy: $2222. Business: $8600. First: $9427.
I promise you Premium is not 3x better than normal economy. I've tried it, it's 1.5x better at most. And business for 12x the price? Yeah, fuck that.
PS: The calculation changes when you work for a Fortune 500 and they mandate/allow business tickets for flights longer than 6 hours. I imagine this is the real market for those tickets because those customers aren't paying with their own money and don't care.