The phrase "grinding LeetCode" refers to a kind of unmentionable self-stimulus indulged in by people who want tech jobs money, but are bad at software engineering, and who want to work with other people who are bad at software engineering.
It was most popular during zero interest rate phenomenon, when there were numerous investment scams based on startup companies that could have a very lucrative "exit" for those running the scheme, despite losing money as a business.
LeetCode falls out of favor when companies realize they need to build viable businesses, and need software engineers rather than theatre performances.
What if I want to work at big tech? Does your message still apply, or if I want to work at big tech, it means I just want tech jobs money, and am bad at software engineering?