Indeed, Mr Money Mustache is a good resource for people looking for an early retirement with an average salary:
Of course, if you are happy living a 50k/yr lifestyle and retirement but happen to make 100k/yr, yes, you should be able to retire much faster.
The MMM lifestyle is something like 25-30k to live.
If you make 50k.. you can save at most 20-25k, taking (10-15 years to retire, would need to do math).
if you make 200k, you can save 150-175k, reaching retirement in 2-3 years.
The "higher income -> higher lifestyle" is a myth MMM tries hard to dispel. You don't NEED newer cars because you make more money. You don't NEED a bigger house. Sure you can choose those things...
Which leads you back to scaling everything up to the number you are willing to you are comfortable with.