I think Jimmy smiths answer is fairly good. I can add a different perspective which might be helpful.
I've been a trainer and tutor for the past 12 years, I have worked with hundreds of tutors and taught over a thousand students, and I can tell you my career is pretty typical of your skilled tutor. Over the course of my tutoring career, I have earned 4 degrees and completed vocational teacher certification.
When I first started back in 2011, I focused on year 5-10 math, and I was paid around $10-$15 per 1 hour lesson privately [0 years' experience, no degrees, no teacher certification].
In 2013, after 2 years or private tutoring, I was hired by a local firm, my tutoring hours increased from around 5 per week to around 20 per week, this firm paid me $20-$25 per 1 hour in home lesson [2 years' experience, 40% undergrad completed, 0% graduate completed, no teacher certification].
In 2016, I was then fortunate enough to take up a resident tutoring position in a local facility, where I was the main math tutor, I started getting around $35-$50 per 1 hour in Centre lesson [~5 years' experience, 80% undergrad completed, 0% graduate completed, vocational teacher certification completed].
In 2019, I then left my resident position and launched my own firm. I was initially receiving around $50-$60 per lessons for in home lessons [~8 years' experience, 100% undergrad completed, 20% graduate completed, vocational teacher certification completed].
Currently I receive around $70-$90 per 1 hour lesson for online lessons, and I have a full schedule essentially every term (20-30 students) [~12 years' experience, 100% undergrad completed, 90% graduate completed, vocational teacher certification completed].
I would expect at the 15 years mark that I will be getting about $100 per hour. I have some colleagues who are a few years older (in their 40s and 50s) and some receive as much as $200 per 1 hour lesson for their work.
If you inflationary adjust these numbers, this is a rough estimate of what a tutor earns across the first 10 years of an average career.