Because why would you want to buy a Dreamcast to pirate or the first MS console which was niche AF (should have called it the anglobox)
When you could pirate a PS2 which was the most popular console? It's not nonsense step outside of the G7 bubble to know how it was back then in most of the planet.
All those kids and teens that grew with modded PS1 and PS2 got jobs as young adults and could make money to afford original games on the PS3 here and there. Would you want to miss the next god of war, gran Turismo or metal gear after 10 years with the brand?
Sony also made some a key decision on the 7th gen. Even more important than all exclusives put together to ensure fidelity on cost sensitive markets: Free online vs Xbox paid. That forced former pirates to make a decision: keep pirating with the 360 (RGH - JTAG) but lose online capabilities or buy less games but play with your friends online for free. Folks chose the latter option. And that's how Xbox basically lost all non core markets with the exception of maybe Mexico.
PS3 could still be pirated with methods like CFW or multiman but 360 piracy was far more popular.
You're acting like Sony intentionally designed their systems to encourage piracy. They did not. You're also overestimating how much piracy actually happened; it may have been popular in smaller markets but we're talking about significantly smaller markets back in the day, who cumulatively did not contribute much to the PS1 or PS2's sales numbers for hardware and software.
In the biggest markets, piracy was much less common in relation to the number of people who didn't have the skills or knew the people to hook them up with pirated games. And, as game rentals were still pretty popular, for many it just made more sense to rent a game from Blockbuster or whatever for a few days, play it, beat it, and return it within the 5 days or so vs. jump through hoops to pirate the game. Mainly because even those getting the games through pirating, still had to pay for the game and/or the service.
And, again, you had to know the right people to even be in that circle to pirate. And also, the situation you describe is absolutely not the only or main reason Xbox lost non-US/UK markets in the 360 gen. The simple truth is, Microsoft didn't give a shit for markets outside of those two, and pretty much stopped trying in Japan after the first three years in that gen outside of getting Square-Enix to make a version of XIII for the 360, and stuff like that. Which would mean, you had a decent number of people in those ROTW markets who were buying the games legit, and felt Microsoft wasn't catering to their needs for printed copies or localization, or advertising etc.
That's been a problem for the Xbox brand for over a decade, actually.