Graduated from a decent college with average grades. Struggled in a tier 2/2.5 firm for a couple of years before spending next 6 years chasing the mirage of civil services exam (UPSC). Restarted career with a tier 2 slowly clawing my way back up to a Tier 1.5 for another 4 years. Now in a tier 1 firm, in my mid-30s settled with 2 kids and paycheck that affords a comfortable life in NCR. So yes, success (with its different meanings and standards) does come at different times to different people.
So if you are starting career now, trust me, you will find your success or calling and inner peace / satisfaction at some point of time in future.

Below average rank here. Mostly due to laziness and disillusionment.(Law firms suck, wlb balance etc). Didn't know where I'd end up. Just gave a few interviews during campus placement and ended up in a T1. Of course I went because like I said, I didn't know where I'd end up. But definitely did not expect to be here. But life is good now, cashing decent checks, but I'm also concerned about my health due to the gruelling working hours. All in all, I'd say is grades don't matter but they do help. But a good cv also matters. You should probably have a wide variety of experiences that can prove useful to the firm