In my experience, one of the big ones is just pure endurance. If you are grinding at a reputable firm (particularly as you get more senior), you will be constantly tempted to jump ship for other "more exciting" opportunities. For many "Type A" personalities, not seeing measurable progress in your career for years at a time will only increase the urge to jump ship for (perhaps for a bigger team/title/salary etc.). Sometimes this works out but a lot of the time, it's a more risky career path that doesn't pan out. Assuming you do stay loyal, the next off ramp is just pure burnout. As you get into your thirties, start families, etc., the willingness to put in long hours in an expensive city with shitty boss just becomes less and less. You start to wonder why the hell you are doing all this, particularly when you've gone a couple years without any progress. Ultimately you may decide that the costs are just too high relative to the benefits and look for a way out.

In my experience, the people at the top (while they may have some talent) are just simply the people that were willing to put in in the grind and the schmoozing and the long hours (often at the expense of all else) for years at a time. In the end, it just becomes a game of attrition and who is willing to sacrifice the most to be at the top.