This is kind of a touchy subject. I feel like a lot of people would balk at the idea of the top 1% not doing better and better, not because they have any extra insight into the topic but because to say this seems like you're defending the ultra-rich (and by extension attacking everyone else). In reality, even if the rich aren't getting even richer at quite the rate we thought, it doesn't mean you really need to have…
If we assume that most people achieve peak earning years between 45-50 years old, then about 30% of people end up in the top 1% at some point in their lives.