Another reason I think there is such a contrast in two groups/opinions on this thread is because in one world (world B) there is something called the salary game, and in the other world (A) there isn't.
In world A your profession has a salary dictated to you. The job has "bands", an advertised salary, and pay increases/bonuses that are pretty much set in stone. So you enter the workplace after an apprenticeship or degree grad program, on quite a low salary, and your salary progression is laid out for the rest of your working days. If you can reach band c, you will get this much. But it's so far from 100k despite years of work. It's predictable, comfortable and it feels nice to have a plan. But 100k, no way.
In world B, salary is fluid. It's like a game of snakes and ladders but you have some control over the roll of the dice. You also start low but you move around the board and you negotiate at every stage. You spend a good percentage of your working time thinking about how you can negotiate for more at your next review. You try to organize your tasks strategically so that you can work them into your performance discussion. You build relationships that can influence salary. So a big portion of your time and effort goes into salary development. Even if you are hired and not self employed, you have to think like you are self employed, you are your own business and you need to be constantly increasing your prices. If at the end of the year you are earning the same, it's not really a successful one.
It's not just hard work or responsibility - nurses and care home staff work incredibly hard and long hours and they are responsible for peoples lives. But the salary is the salary. No matter how hard they work, the pay opportunity won't change.
It takes a certain kind of personality to succeed in world B. You're not just working hard but also strategically. Lots of people saying they are earning 100k and working in finance or law. Well they have learned to think that way through their studies and from early exposure in the workplace. If they weren't strategic by nature, they wouldn't have made it into that field in the first place.
There's no point on high earners being smug about their hard work because many low earners work hard too. You could say you are smug because you just had the right thought paths in your brain to play the game, and were fluid enough in your decisions to take the right ladders and avoid the snakes.
But I also agree with posters that say growing up in hardship can make you successful or a high earner - if you spent your childhood having to be inventive and avoid obstacles then you are more likely to choose a career path where those skills are relevant.