Look at Adobe, for instance.
A good portion of their user base got started using cracked copies of the software, as the price of something like the CS6 Master collection was well outside of the affordability of the average hobbyist.
But some of those teenage hobbyists grew up to go to college to expand on their Adobe tinkering to becoming professionals that sneer at people who use non-adobe products because of the price.
Businesses buy the software because that is what the talent is trained on. The difference between calling what Adobe has on the market a monopoly and an actual monopoly is probably only technicalities at this point.
Sure, most of this comes from the fact that their software really was the best of the best for the longest time, and their lead in technology and namesake is so far ahead of any of their competitors that it is laughable. their software was pirated obsessively because it was so good and so expensive, just like Waves $2,000 Mercury VST plugin suite.
There are other softwares, many of which are free or very affordable, that do 95%+ of what anything adobe or Waves does. But when you edit a photo with Gimp people will still instinctively say that you photoshopped it, and few people will ever care what plugins you used on an audio track if it's not autotune.