That's true to a point for everyone: that having more money from a low starting point primarily increases lifestyle. But as you add more and more money, I think that most people reach a turning point where "enough really is enough" and their worries about money truly diminish, but that lifestyle stops increasing.
As I've grown in my own career, for sure my lifestyle increased. I literally subsisted on Ramen and $2 frozen pizzas in my first startup. Then as I achieved more income, I added a convertible, then a 401-k, then a new SUV (worst decision to that point), then a first house, then maxing out 401-k, then an airplane, then a classic Mustang, then a city apartment because my house was too far away and I got tired of the constant commute, then moved to a house in the city, then had 2 wonderful kids, then added 529s (college savings plans), then a bigger airplane, then...
All of those things, except the 401k and 529s, also came with additional expenses in time and money. (Technically, those 2 did as well, but in an immaterial way compared to orchestrating the maintenance on a house, classic car or airplane.)
However, I can also see that increases in income from here won't go towards (current) lifestyle inflation, as we have "enough" now. That could be because I'm older and wiser now, rather than a natural knee in the lifestyle vs income curve, but I'm inclined to think it's a natural knee.
For very few people does that knee hit before $100K/yr in a major US city. I'd guess that for a great many people, it doesn't hit until after $250K/yr, which is why people for shorthand say that it doesn't exist.
If you'd like to challenge yourself to bring that knee closer to the left side of the graph for yourself, I recommend Mr Money Moustache, Len Penzo and JLCollinsNH as bloggers who write extensively (and well) about this topic. Quick Googling will find them all.
I believe that getting to the right side of that knee, where you can stop worrying about money, is worth so much more mentally and emotionally than any amount of lifestyle inflation (beyond the basics of food and shelter). So, whether you can manage to increase your income to pass to the right of the knee, or move the knee to the left of your income, either way you'll be happier than a new car, new house, splendid vacations or 100 great dinners out.