Neat graph. It doesn't seem to fit me. And you know what. It is not supposed to fit any body.
Taking my example as a real world use case, I started working just before 1980 way below the bottom line. I was working part time at McDonald's making $3.15 an hour. Then I took a job with the same wage but more hours at a grocery store. I did part-time work as a photographer. (No company, just me) Then I worked in a Target using my photography skills to sell cameras. While doing that I taught myself about computers. Then I invented a better job teaching a small business how to use them. But really I'm too lazy for that kind of work so I went to the university. I had no money and there was a recession so I took out loans to get a degree in computer science. I could have gotten a lamer degree with much less work. I know, I had lots of roommates. But I decided not to throw my money away. After school, I got a better job and paid back my loans. After that a better one. Then a better one because my skills kept growing. So after 30 years I fall between the top two lines.
I'm not exactly Steve Jobs, but then again I didn't re-invent several industries either.
Now, if I was still working the grill at McDonald's doing the same damn thing I was doing 30 years ago, I'd be making about $7.25/hr. That would be more than a 100% increase over those 30 years. Now of course you'll claim that 100% increase hardly matches inflation. Shouldn't I have gotten much better raises over time having 30 years of burger flipping experience. Clearly, after 30 years my burger flipping skills are way more valuable than those of a high schooler starting his first job.
I can only reply, No. Indeed they wouldn't be. I was a pretty fucking good burger flipper. There was very little room for improvement in my burger flipping skills. If I was still doing exactly the same thing, it would be worth exactly what it is worth today. But at least the job would be easier. I watch them, their equipment is way better now.
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Feel free to tell your own tail if you wish.