I look at the skillset between when I was 25 and now (30) 
    and it's astounding. I can't imagine what the difference
    between 50 and 25 will be.

While it's true that there's some new tech/tools coming out, stuff doesn't necessarily change that much...I started working as a programmer at 18 (I'm 33 years old now) when the popular new thing was java.

In between I used many different languages and tools (c, c++, python, matlab, js, haxe, as3, in no particular order & probably some that I've forgotten) but now I'm using c# which very in-vogue in my line of work (game development, due to the popularity of unity) and it was a virtually seamless transition from java (I actually started using c#/.net in 2009 as a tools programmer independent of unity).

EDIT: nevermind, I realize now you meant you improved drastically in 5 years, not that the tech field has changed drastically.