I'm impressed by your motivation until now Rol, to try to figure out the answer to the universe, which is exactly what it takes to find out what makes a console successful. I respect your effort and am always happy to see other humans wondering the same trivial questions as me, while coming from a completely different culture, country, world.
My two cents, it's about trends. The reason why compagnies succeed and then drop in this market is because trends change, and while some companies follow the trends, others meet them in fragments of time
For example, when the NES came out, games like Mario and Zelda were revolutionary, cultural phenomena that arose at a point in time and made their mark. Then, the SNES followed up but while the games were an upgrade over the prior generation, they did not have the same impact. Now compare that to Pokemon, a game that came out on a much weaker system than the SNES and even the PlayStation, but was a massive phenomenon, even until today, and allowed Nintendo to weather the toughest entrepreneurial storms.
The Wii was Nintendo's chance to make its mark again but they didn't manage to catch lightning in a bottle and let the ball drop.... But finally the Switch came in with the right design, practicality, style, and library to back it up, and all the stars aligned while Nintendo probably didn't even expect it.
The PlayStation played all the cards right from the start to make noise. They had multimedia playback, targetted sports and simulation fans, this opened gaming for other people to turn their heads, and also allowed Sony to usher older Nintendo gamers towards the next experience. However trends make it that people are getting tired of the same old experiences, so they are turning to other forms of entertainment. Still, the PS and XB maintain a certain level of popularity even while things have calmed down. The future obviously belongs to the PC due to its versatility and the diminishing returns barrier. Nintendo is in the best position it has enjoyed since the NES and is here to stay as the new banner for games, and will likely be so for many generations to come. The reason is that Nintendo is on the trend and will ride, surf and even drive it for a few years, even generations. They're on top now.