I think the cycle is general, not specific to Google.

The people who build a successful business attract others by that success. The 'others' weren't attracted to the company for the same reason as the builders, they are joining because prestige and money are there already. These people change the culture of the company from prioritizing the things that made it sucessful to prioritizing prestige and pay of the 'others'. This distortion then makes things weird. The reputation of the company tarnishes. The builders no longer opt to join due to the weirdness. Now, all that is left are the 'others'.