Having said that, if you work for a big high-tech corp (like I did, although I never worked for Google per se), you will find that it is hugely difficult and frustrating to push your own idea through the system.
Google could afford to take all the other ~95% of Great Hackers by paying a high salary until the project is either killed or a success. The big problem is that Google doesn't fire people for failing, they just move them around like most big companies do. They suffer from the "good effort" syndrome, where people are rewarded for "trying" even if when they fail to produce "something users want".
If you really want to build something new and interesting, you should be willing to make financial sacrifices to make it happen. If you're comfortable, you probably won't be as hungry.
It's still no substitute for people who want to do real startups. But a good salary during the effort is a great way to attract all the great hackers that need reliable income.
Getting a big check or a pink slip at the end is ideal.