And perhaps "bet" is the wrong word being used here. Usually with a bet in gambling terms, you either win big or you lose it all.
When Alphabet tries a "moonshot", they come away learning a lot about whatever problem it is that they were trying to tackle. They build expertise in-house, and they flex the idea muscle within the company. That isn't zero-value activity. In fact it's very valuable.
$1B a year is a small price to pay for what could eventually spurn a sustainable $10B per year or $40B per year business in the future (self-driving cars, for example).
Now this is just me being optimistic. It could also very well be the case that the X division is horribly mismanaged and the moonshots fail for more nefarious reasons, but I'm willing to give Google the benefit of the doubt.