Think of the investments in Loon, Taara, SpaceX and Google Fiber as part of a larger strategy to bring internet access with decent bandwidth to a larger number of humans. Some investments will not pan out, others will bear fruit.
Does this make sense for alphabet? I agree that it does as one of their many bets.
Does it make sense for Loon which spun off as its own company under alphabet with its own leadership and its own stock? That’s the strategic failure I’m talking about, Loon’s not alphabet’s.