By being very good. Mostly the Uber-geniuses thing, but I wouldn't call them geniuses. You do have a bit of the harder working but it's quite minor and of course sometime you benefit from being in the right place at the right time (luck). I'd say elite network is probably the least important conditional on you having a decent network that you can get at any top 20 school if you put in the effort (be involved in tech societies etc.)