Mix of quality games and competition breaking all levels of stupidity you can imagine for a gaming company

Plus Sony was open to take a risk entering in european market full force, a market Nintendo and Sega pretty much neglected. It paid them so well other companies can barely compete with Sony in Europe until today

Definitely Sony getting 3rd party deals like Final Fantasy and Metal Gear Solid, among many others that never made their way to N64. A combination of Nintendo’s cartridge format being limiting and Sonys love for moneyhats.

I can't tell about the rest of world, but for sure in Italy it's easy to understand.
- Better marketing: lots of ads during prime time in most popular evening shows.
- Better distribution: PS games were avaliable in almost all small to large computer and electronics shops, while N64 was distributed by a local toy company and its avaliablilty was much more limited and restricted to toy shops
- The price difference for games was insane (due to both cartridges and intermediation costs I think), I remember some new N64 game could cost up to 3 times a new PS1 game.
- Language barrier: the PS1 was the first console with full localization on all titles, when I was a kid it would have been impossible for me to play a game like FFVII or MGS in english.
- Of course 3rd party support
- The value of having a CD player. That could seem irrelevant but it was a big deal at the time.

The PS1 tapped into a new age group for console gaming. Smart marketing, more 'mature' games and the (unintended) ability to pirate games made it a great success. The ps1 was promoted in night clubs in Amsterdam where you could play GT1 while chilling out.

Nintendo was still seen as a kids toy, plus cartridges were far more expensive and no piracy. PCs were still very expensive to game on. In Europe PS1 basically took the Amiga crowd when Commodore became less popular.

As a former Nintendo fanboy, it just wowed me. At first I was probably like many gamers, "What the hell is this PlayStation with it's stupid looking controller." I was 100% going to get a N64, probably Ultra64 at the time. But, I 2ent over to a friend's house and his nephew was there with his PS1. I kinda scoffed at first. But then I actually tried it. The controller felt so good. Then, I played Tekken, Alien Trilogy, and some helicopter game. Watching the cinematics blew me away. As did playing those fun games with that controller. Ever since that day, I've been a PS fan.

Strong 3rd party support
Quality 3rd party games
Better adverts
Better games
Exclusives

PS1 sold a lot in third world countries because of cheap pirated games. In the Philippines, you could buy a PS1 console in cheap electronic shops and PS1 games for 50 pesos (around $1.25 that time). PS1 could not have achieved its 100M+ milestone without these pirated games.

A bunch of reasons:

1) Sony were big in electronics and the PS1 offered a CD player as well a console from a world class brand. Sony has the best TVs, Laptops, headphones and walkmen.

2) The PS1 hit kinda at the peak of the arcade scene where you had street Fighter, Tekken, Time Crisis etc and it offered the arcade magic at home from light gun games, racers, beat em ups and dance mat games.

3) it was cheap

4) it had better tech than the N64 and the Saturn couldn't compete with soul caliber, ridge Racer, time crisis etc. Whether it was due to being in direct competition with Namco or Sony. Sega got hit from all angles.

5) it was the first easy to play pirate games. I knew over a dozen people who had pirate games for it and it was so easy and risk free.

You say that, but it really is hard to imagine that a newcomer would just come out today and outsell the PS5 and Switch out of the gate.

Well, it's been pointed out before Sony wasn't actually a newcomer. They had been dealing with SEGA and Nintendo for years in both hardware and software prior to PS1. Microsoft was not a newcomer either. From the MSX in Japan in the 80s. From PC gaming to working with SEGA on Dreamcast and then using DC's in focus tests for Xbox. (hell,XB was almost BC with DC games) Nintendo had arcade experience. Game & Watch. Pong clones. SEGA had arcades. So each console maker had a warm-up period before entering console gaming.

Google Stadia does not understand it's the audience. It was created by executives with no knowledge or interest in gaming. Google had no real experience. They hired the Vince Russo of console launches with Phil Harrison to be in charge and yet wonder why it struggles lol. For context. Vince Russo destroyed wrestling companies like WCW and TNA. Phil Harrison helped with the disastrous launch of PS3, Xbox One, and now Stadia. Only after Phil left Sony and MS did things start to improve.