WWE is the biggest promotion in the world of professional wrestling today. John Cena is indeed one of the biggest stars the promotion has ever produced. But the road to achieve the ultimate success was never for The Champ. He himself revealed his struggle stories in WWE many times.
WWE might have been the best professional wrestling promotion in the world but surviving in the best in the world is equally difficult. There are hundreds of example where wrestlers completely failed to succeed in WWE but outside they became really big stars. WWE can create wrestlers like John Cena and Roman Reigns but not everyone can achieve that level of success.

Big WWE Star Makes Shocking Statement: You Must Want To Be Like John Cena If You Want To Be In WWE
WWE Superstar and one half of the WWE Undisputed Tag Team Champion Sami Zayn recently discussed what type of mind set new wrestlers have to keep in their mind when they start working for WWE. He remembered his own time from the NXT and revealed what was the mentality was. Speaking on WWE After The Bell with Corey Graves, he said;
“I remember when I got to WWE, it was NXT or something like that, it was very much the mentality of, ‘you should be furious that you’re here. You should want to get out of here. You should want to get on the road. Everyone around you is your enemy, they are all vying for your spot.

“This is a competition. You have to be the best to get out of here. If you don’t want to be the best, you shouldn’t even work here.’ I remember a line something to the extent of, ‘If you don’t want to be the next John Cena, you shouldn’t even be here.’” Said the former two times WWE Intercontinental Champion.
“I remember hearing that and being completely [mouth agape]. ‘What? This is insanity.’ Let’s just say we’re in a room with 100 people, let’s just say the next John Cena is in this room. There’s only one, so the other 99 people in this room should be miserable at all times trying to aspire to be that person? What kind of insanity is that?”

Most of the big stars WWE created like John Cena and Stone Cold Steve Austin had their own stories of struggle. But parallel to WWE, new promotions like AEW have also started to grow which provides the wrestlers more opportunities to rise, and it is definitely good for wrestling.
H/t to Fightful