I can see your point, but I think El Bulli is a little different. Ferrán Adrià is a chef and not just an owner. I can't honestly say if he's sweating it out in the kitchen every night, but from what I understand he is there behind the months of preparation of the menu for each year and, at least for a long time, actively participated in the cooking. It may be that after all these years he has delegated the cooking to subordinates, but I really can't say.
I agree 100% that the term "best" is almost absurd and obviously totally subjective (an I'm certainly not saying El Bulli is the best), but going to his restaurant is apparently an unparalleled experience, and if there are now hundreds of El Bulli-esque restaurants around Spain and the world, it is certainly thanks to him. His achievements are hailed almost universally by experts, and his contribution and influence are immense. So, personal tastes aside, we are before a titan in creative cuisine, not just a very good chef.
Is 150 € worth it? That's certainly up to the individual, and if someone doesn't think so, it would make perfect sense. I think many restaurants are overpriced and I can't stand this trend of fancy food (or not so fancy food) costing an arm and a leg. But from a luxury standpoint, relatively speaking, it is not totally beyond reason, when you compare it to what other luxuries might cost. And even then I think it's borderline justifiable.
But of course, these are debates that have been going on for a long time and I get the feeling there is really no one right answer.