The PS1, despite being Sony's first foray in the video game industry sold an amazing 102.5 Million Units and is still the 5th best-selling console of all time and 3rd best selling home console of all time. 

To me looking back it seems surprising to me that the PS1 did as successful as it did being Sony's first time in the video game business and pretty much killed the huge console brand Nintendo at the time beating the N64's 33M with the PS1's 102M. Nintendo was so big at the time to the point where video games were just referred to as a "Nintendo" from what I heard and for Sony to just easily take that throne from Nintendo seems quite amazing to me even to this day.

To those who lived and experienced the 90s, when did you first hear about PlayStation and what made you immediately trust Sony with the PS1 enough to buy one? And did you skip out on the N64 for the PS1? What do you think made PS1 so successful to beat out the well known and dominant Nintendo brand at the time?

N64 had limited space on carts plus NOA policies were shit. SEGA Saturn was expensive and had a very difficult hardware to develop on. Sony's machine was easy to program for. Cheaper than Saturn. Killed SEGA at E3 with the infamous $299 after SEGA announced Saturn was $400 and launching the day they announced it pissing off retailers. 3rd parties (esp key ones like Square from Nintendo) flocked to PS1 for these reasons and more. Sony took advantage with better marketing and the fuck ups of Nintendo and SEGA.

Sony wasn't new to gaming either. They worked with Nintendo on the SNES Soundchip and the canceled CD addon. They worked with SEGA on SEGA CD games and for a brief moment were going to work together on the Saturn.

Final Fantasy VII

SEGA, MS, Nintendo, and Sony all had some gaming experience before becoming console makers. SEGA with Arcades. Nintendo with Pong machines, Game & Watch, and Arcades. Sony worked with SEGA and Nintendo on games and hardware. Microsoft had the MSX in the 80s and PC gaming. So none were new to the industry. They had an idea of what to deal with going in.

Because of the cartridge choice over CD. 

Price of games. Most ps1 titles were $40-$50 while N64 were $60-$70. Big difference.

In addition to that many third parties migrated to Sony over Nintendo due to format differences.  The SNES had excellent Square Soft, Capcom, Konami, etc. support.  But the N64 lost all that.  Had the N64 been disk based, I don't think Sony would be who they are today.  It was a massive mistake by Nintendo.

I also think the PS1 was seen as the more mature console. The same thing that helped the Genesis at first. But unlike the Genesis, the PS1 didnt have to compete with a console like the Super Nintendo. Plus many of the reasons listed by others here.

I don't think this can be overstated. And it's not because it was a sequel to Final Fantasy games.  I barely knew anything about the FF series.  This game was phenomenal, it was cinematic, it was heart pumping glorious art.  Few games can reach the level this title did, even to this day.  And there is a cinematic in this game that rivals the emotional feeling of all videogames and most movies.  It's just that good.  I think for some folks who maybe entered the gaming scene after this, in let's say the PS2 era or later, that the blockiness of the game can leave people wondering "how?" But at the time it was revolutionary, there was nothing like it, and it was an instant system seller.

"Final Fantasy 7 was the rare game that exceeded all expectations. Its release coincided with growing awareness of Japan’s pop culture, particularly anime. As a cyberpunk story about personal delusions, mental illness, climate change and class warfare, it was Blade Runner for millennials. It single-handedly put role-playing video games on the global map. Moreover, it helped the Walkman company rebrand into a gaming titan."

https://www.washingtonpost.com/video-games/2020/04/03/final-fantasy-7-legacy-creators/

Basically.

To add a bit, FFVII is also a bit of a poster boy for the fact that third party on masse went to PlayStation for a variety of reasons, which gave it a massive edge over Nintendo. It's quite simple.

PS1 was kind of a slow starter compared to todays consoles. N64 shipped more in it's first 2 years than PS1 did... just that by the time N64 launched PS1 was just hitting it's stride.

So:

Earlier release (or more specifically late release of N64... PS1's competion was the Saturn & the aging SNES)

Discs (allowed for better sound & more space but also allowed them to sell the games using the video cutscenes)

Discs again, as they were cheaper for 3rd parties = more incentive for publishers to make games for it.

Nintendo's prior treatment of 3rd parties no doubt also played a factor

Sony's already existing huge worldwide brand power, Nintendo only really had a strong Japanese & US presence. This also extends to availability, I think back then apart from Japan, USA, & the big 5 in EU Nintendo didn't directly sell in any other countries... I think they had a partnership with a company to cover Scandanavia, and maybe Canada came under NoA umbrella... the rest of Europe & rest of the world would only be able to get grey imports.

My experience as a Nintendo fan;I didn't care about the Saturn and PS1 (or any of the other systems that tried to get a piece of the gaming pie). I saw what the Ultra 64 was going to do and that was all that mattered. Then the N64 launched and...it didn't deliver on what the arcade machines promised. It wasn't even close to what they showed for Cruis'N USA or Killer Instinct. I was still satisfied for the most part. Then I found myself going to the store looking for new games to buy and coming home with nothing. Not even new games to get excited for.After Mario Kart 64 disappointed (IDGAF what anyone says. The game didn't deliver), I ran out of stuff to do in Wave Race, Mario 64, etc., and Killer Instinct Gold was extremely disappointing and cost $80, the PS1 started to look pretty good. I saw games like Tomb Raider getting high scores. Then, my friend/neighbor let me borrow his PS1 overnight to play Tekken 2. HOLY SHIT. The CGI cutscenes! The awesome animations! The music!! I wanted a PS1 so bad. And they were totally sold out. I bought two games before I even had the system--Tomb Raider and Resident Evil and they only cost like $30+ each. I just looked at those shitty black and white manuals and listened to the crisp Tomb Raider soundtrack over and over again on my CD player. By the end of 1997, my N64 was gone. I would buy another when DK64 released, though. But by that time, the generation was pretty much over.