Now as glib as that sounds, let me clarify. In the valley hiring has become extremely focussed towards attracting "talent" but in the FAANGs there is really no way to qualify experience unless you are a brand (inventor of X, co-founder of Y, author of framework Z). Unfortunately also in the FANGs the stacks are extremely customized (after years of picking and choosing what works for said companies), so even if you had a lot of experience you may not be aligned (perception here) with the companies' venerated stacks. This leads to the situation where there is not much room for specialized folks (unless you are again the branded ones). In this situation there are very limited ways of judging candidates in a standardized way. Lo behold puzzles and leetcode! Many companies (in the FANGs) routinely reject experienced candidates who cannot solve leetcode problem # (put in your favorite problem here).

This is for the FANGs and FANG wannabees. At startups the scene is different as you dont have a scaling problem with recruitment so leetcode is not the focal point of your judgement. But you asked how to make "big" bucks and not quantum money!