Firstly, there could be financial milestones, career milestones, but I dont think there is necessarily 'salary milestones'. For some, reaching a $5K salary may not even be within their lifetime. To your own point, such mentality does seem a little 'toxic'.
Secondly, it does not matter what age you earn that salary. You should know that some career comes at a price - the more you earn may not necessarily equate a better quality of life. ie. what is your real purpose of earning so much when you are young? Are you missing out on something else?
Thirdly, you don't necessarily only need to focus on scaling your salary in a career. S ome took u-turns or suffer a pay cut to get a job that is more enjoyable or fulfilling.
I'm happy that you achieved a high salary at a young age, but I will encourage you to try and get out of that rat race. Most of us are kinda stuck, but you could have a real opportunity to do better.