Ed Viesturs' biography, "No Shortcuts to the Top", covers this well - you can see how he saves money, works various jobs, and pursues sponsorships to fund his Everest, K2, and other big-mountain expeditions.

He'd get a trip all organized, then it will be aborted mid-climb due to weather or other issues, and he'd have to start all over again and take a few years until he can try again.

It's also just a good read if you're interested in the topic.