Depending on the configuration you may have a real (narrow) bed feeling, or you may be lying in a sort of tube with not much space to move, but definitely completely flat.
If the price is not outrageous I always go for a business flight on long haul.
Absurd means in the 6000$ range from Europe to Asia and I agree that's over the top compared to, say, 700$ economy with a reasonable airline.
Then again upgrading is an option and sometimes really great bargains can be found.
I flew Zurich Bangkok return with Oman Air in business for less than 2'000 in February. In my opinion a very reasonable price for a great product.
Also funny how you yourself come up with the ridiculous salary of $500k, something ~nobody here will ever make, as the amount that finally makes $3k sound trivial to you. I agree with that much. That's the salary that would make me finally consider paying $3k for leg room.
You need to be level 7+ in a FAANG anywhere else in the world to make anything near that. And you definitely won't be there with "a bit of Javascript".
Now, business class or whatever they call the thing where you can recline your seat almost horizontally, that's something. I can't really sleep sitting.