It's hard to quantify the amount of sales lost but you're delusional if think piracy does not affect game sales.
"Pirates would never buy a game anyway"
"Emulation is primarily for game preservation"
lol. lmao even.
It's not that piracy doesn't affect sales in the sense that "No one will ever buy a game if they can't pirate them". I'm sure there's a certain percentage of users that will do exactly that.
The problem is that this would be just a face of the coin. It doesn't take into account factors like:
- people who actively avoid DRM
- people who don't care even remotely either way
- the fact that even if just "forced to buy" most people have only so much money they are willing to spend on this specific hobby and they would make choices.
- the "cultural penetration" element for which even people who pirate something may talk it up to others. I'd bet that more than negligible amount of sales over the years was "inspired" by someone who pirated a game and then praised it to others, leading to more sales. No one goes around praising a game they have not played first-hand.
For example the PS1 and PS2 climbed to be colossal success stories for Sony because -among other reasons- compared to all the competitors of their era their games turned out to be trivially easy to pirate.
The thriving pirate market for PS1 and PS2 software is precisely part of what made their meteoric rise to popularity. And while this meant some people would get some games illegally, it also means that after a while there was a far larger user base willing to spend money on the platform.