Software a stagnant field for 15-20 years? The single most used computing platform in history (modern smartphones) only began to exist in 2007, when the first iPhone was launched. It took several more years before it was mainstream and then ubiquitous. Plenty of software coders and software companies have made their fortunes on that enterprise alone.

That's the consumer/retail world--in the business world, cloud platforms like AWS are the most important development in recent history. I'm not a business analyst, but last quarter Azure was responsible for something like 15 billion in revenue (out of some 37 billion in total). Microsoft introduced it barely 10 years ago. The counter-example is even more illustrative--history is littered with software companies that didn't change or add to their core products, and no longer exist.