From my point of view the store model simply is more convenient for consumers and worth the extra price. I know that I stopped pirating games, music and movies when I started using Steam, Spotify and Netflix.
Don't know about I_Byte, though I could have written what he has written.
I can now actually afford games (in the quantity I consume them) now, so that question is fair. But thankfully the video landscape fractured, now you better have NowTv, Netflix, Prime and Disney+ and you still can't watch all. I've started pirating again after 10 years or so of complete abstinence. So I think it's causal (if you have money)
With games, an important part of the equation is DRM. I prefer buying (DRM-free) things from GOG where possible, but steam has provided developers with a decent bit of DRM that is not too intrusive for consumers. There's plenty of older games from before Steam became dominant that I refused to buy because of their draconian DRM solutions.
I have to say that Spotify completely changed the way I listen to music, and I would really struggle to go back to buying individual albums.
I think of the three, movies are the only one where the "more disposable income" part of things is the dominant component of why I changed behaviours.
This makes me think of GabeN's 2011 commentary on expanding Steam into notoriously hax0r-infested Russia: the smart money scoffed at the prospect, keenly aware that the Russkies will just steal your product and why not make it that much harder for them to get their hands on it?
“Russia now outside of Germany is our largest continental European market [...] The people who are telling you that Russians pirate everything are the people who wait six months to localize their product into Russia. It doesn't take much in terms of providing a better service to make pirates a non-issue.” [0]
"We think there is a fundamental misconception about piracy. Piracy is almost always a service problem and not a pricing problem," he said. "If a pirate offers a product anywhere in the world, 24 x 7, purchasable from the convenience of your personal computer, and the legal provider says the product is region-locked, will come to your country 3 months after the US release, and can only be purchased at a brick and mortar store, then the pirate's service is more valuable." [1]
I for one absolutely have more money than I once did, but to be honest I stopped pirating long before that in '09 or '10, once I realized that the then-ridiculous Humble Bundles and Steam sales reduced the actual expenditure required from "gotta save up" to a mere "gotta skip buying takeout tonight". Of course the sales have decreased in quality since then, but so too has the number of games I want to play, and the time I can spend doing it.
I still pirate most movies and some TV shows because the selection on streaming services is bad, particularly for movies. I don’t pirate many new movies, it’s almost all back catalogue stuff.
I don’t pirate games and music because Steam and Spotify (or Apple/Amazon music) are a better experience than piracy.
But is it a causal relation? You probably have a steadier income now than you had back then.