When the supply >>>>>>> demand. Big 4 have the luxury to choose from huge talent pool. It's normal that 90% of candidates to be rejected. Upskill yourself from somewhere somehow, then reapply with your strong CV offering what they really want. They, after all are still a for profit business entity looking to make money, and you suppose to make money for them

I too got rejected without even a call from them. It's either my CV too terrible or probably my terrible uni results scares them away.
Didn't get dejected, that set me on a path to entrepreneurship and I earn much more than all my ex-uni mates combined that graduated with flying colours that still working with big 4 till now.
I'm not discouraging applying to big 4. If you get it, fantastic, learn as much as you can and utilise it to chart your own future that you want. Certainly it is nice to have guidance being there rather than on your own with no help. It speed up knowledge and experience acquisition. However, being on your own imbues tenacity, perseverance, and strong attitude, that is if you don't give up.
Young people, combine the best of everything, and you all would have a recipe for success in whatever you do.
If you don't get it, don't be disheartened, when a door closes for you, there is always another window open for you. You just need to climb through the window than just open the door and walk through it