"Other bets" are Alphabet's bets on things that do not relate to search, or necessarily to organize the world's information. There are, for example, self-driving vehicles in the form of Waymo. Loon balloons to provide internet connection in poor parts of the world. Drones in the Wing, and much more.
In my opinion, companies do not exist just to earn the maximum amount of money. They should also benefit society and humanity.
Obviously, to do that, they need to make a profit and have a working business model. But Alphabet is spending some of his billions ($ 15 billion so far) on important developments.
If it hadn't been for Google, self-driving vehicles probably wouldn't have come as far as it does today.
After DARPA's competitions that pushed the progress of self-driving vehicles forward, car companies did not lift a finger to continue that forward motion. The only company that did was Google, which today is Waymo.
Thanks to this, all car companies are now pumping billions into the development of self-driving.