I flew business class with BA five years ago as it was cheaper than economy on my usual airline at the time (EK) - mainly as it was a last minute booking. I flew two intercontinental legs (Middle East -> Europe -> North America) and both aircraft were on old 747s that looked like they hadn't been cleaned for a week or more. The infotainment system felt just as old, with a choice of maybe 20 movies on the 8" display where the touch screen barely functioned. The lie flat bed wasn't bad (they had an interesting layout where one seat faces foward and the next faces backward), and the food was just regular reheated meals with slightly nicer silverware than economy.
Now I understand some other airlines have better offerings than BA, and if you fly first class (I think for the same flight it was roughly 8x more) it's going to be a different story, but at the end of the day you are still just flying A to B.
The best part was probably the lounge where I had the connection, but I only had 1 1/2 hours so didn't get to experience it much. However it wasn't really much more than a 4* hotel buffet.
If I could afford to drop $20k to fly first class whenever I feel like it, would I? Probably. Do I feel like I'm missing out on anything by not doing that? Nope.
How much more is it to fly in a private jet? I feel that would be a different story, given you can schedule it so it picks you up whenever is convenient for you.