Theres a few differences between Intel and Google here. The first two points are from Peter Thiel:
1. Google really didn't know what to do with its excess money, which was why it was just stockpiling it and not using it to invest in its own business.
Intel, by contrast, always knew (at least in the Noyce/Grove era) what to do with its money.
2. Google's "side projects" were false-flags and smokescreens to make it look like it wasn't a monopoly. (Thiel says it much better himself in his article and speech titled "competition is for losers"-highly recommended).
Intel did a similar thing around the turn of the century, when it started making ARM chips--not because they were the most profitable thing they could be doing but because they didn't want to look like a monopoly.
And, of course, you really hit the nail on the thumb here:
> Of course the founders have majority voting shares
Yeah. The executives of google and facebook just don't face the same accountability from the shareholders that the execs of any honestly-governed public company does.
Its a two-edged sword: if google or facebook needs to spend a lot of money to pivot, they have the flexibility to do that in a way which other companies don't. However, the flip side implication is that, e.g. Zuckerberg can just spend $10 billion on a huge project, without being at all held accountable if it fails.