I think neither sales nor profits are the correct way to measure which console is the most sucessful.
A console is not a business, a console is a product, so the tangent of "what is the purpose of a business" is pointless for this discussion
The most sucessful product is the product that archieve the best all the things it was planned to archieve. For instance, if you release a product with nothing but to advertise your brand then the product that brings in the most engagement will win
The purpose or PS2 was not only to destroy Nintendo's market share and complete Sega destruction, but to leave Sony brand to market where no other console have a strong footstep. The outcome was:
- Nintendo leaving the Red Console Market (high specs, focused on strong hardware and technical accomplishments) and dedicating themselves to make their own thing as much different as possible from Sony
- Sega exiting console market
- PS2 selling more than any other console in story outside USA and Japan
The only thing they failed to do was to stopping Microsoft to grown. In reality despite the sales OXBOX left its costumers happy enough to turn them into fans of the brand who were ready to buy their true breakthrough X360
So in all, PS2 manage to accomplish almost everything Sony intended them to do. I'd say PS2 was the most sucessful Sony console, but it wasn't the most sucessful Sony era. Why? Well, it's not like PS2 plan was perfect, Sony miscalculated two things: Third parties having no proper allegiance, the fact first party are important to solidify a hardware brand
I think during PS2 times it was common for 3rd parties to relese their games only on one platform, as such 3rd parties exclusives could drawn interest for consoles this lead to Sony neglecting their first party output as their main concern was to bring in as many 3rd party blockbusters arls possibles
As the market changes drastically from 6th to 7th generation as well as very good business decisions from both MS and Nintendo Sony should have realized that maybe their strategy for PS2 wasn't exaclty the best way to manage a gaming business
It leads them to PS4. With PS4 they wanted to strength their IPs and they absolutely made it. Sony is now in a position they can release a new IP and sells 5 million comfortably as if it was nothing, not even Nintendo can do that as they rely in good WOM to sell their new entries.
Moreover, Sony plan with PS4 was to make people spend with software and goddamn it people are spending a LOT with software. The plethora of 3rd parties available combined with lower priced games after are mitigated buy the bunch of MTX and DLCs existing on Sony ecosystem. People on internet always rage about how evil MTX are but the market clear screams to be unbothered by MTX, alas the market in reality seems to LOVE them, last year add-on content made staggering 8.3 billion in profits against 6.2 billion from software sales and 3.2 billion from network/services.
So Sony is now in a position where they have a very healthy and profitable subscription service, very good software sales as well as third party support and their IPs are stronger than ever. Sony might now have the market dominance they had in PS2 and PS2 might be a more successful product than PS4, but Sony as a gaming business seems in a healthier position compared to PS2 era as we can see by how well they are transitioning to PS5
