My personal reason for not pirating IDA Pro is because I don't want to contribute to the problem. It's one thing to argue about the effects of piracy on things like video games, where the unit price is much cheaper, and a large number of users are casual users who mostly are going to buy legitimate copies if it's convenient and not exorbitantly expensive.

Power user software, like Photoshop, IDA Pro, VMWare, etc. are a different story. They provide tremendous value to both companies and individuals and yet I have no doubt an enormous amount of their poweruser userbase simply have never paid for them. As a young adult or child with no practical way to get a license, this is pretty innocuous since frankly it's hard to argue any sale was lost. But there's plenty of cases where large companies and of course hobbyist users end up pirating the tools they use. I believe Windows XP shipped with some audio files that were produced with a pirated version of Sony Soundforge, for example. That's just silly, but.. it happened.

IDA Pro is an excellent piece of software. They provide a freeware version, which is a pretty nice thing to do. And while the licenses are expensive I have no doubt it is worth it to the companies that purchase it, many times over.

Sadly, I can't afford IDA (as I've discussed eerily recently in HN comments, actually) so I've been mostly avoiding it for now, but I do buy other software, including Windows licenses, Adobe Creative Suite, VMWare, etc. If they're useful enough for me to use, then as an adult with decent income, I pay for them.