Investing in a bubble is a good thing, though. Without it we'd have no Paypal (and hence no Musk).

It's great for technology and society. It's not great for you when you invest your own or someone else's cash on the wrong side of the burst.

Sure. Growth in value, as measured in users plus at least one of profits or strategic value. I see Tesla, SpaceX, Twitter, and Github and I do not see a bubble. Instagram and Tumblr are good examples of growth in strategic value being enough.

I don't actually see the separate and distinct economic value creation in Instagram, Twitter, or Tumblr, nor do I see the economic value capture in Github.

But Tesla and SpaceX are just fucking awesome.

The economic value of GitHub is in making team collaboration and communication, the primary bottleneck in team development, that much more efficient. That is hugely valuable, as it increases the economic productivity of companies writing software, and allows teams to organically form (and dissolve) without much organizational overhead. It is a huge improvement from the days before SCMs (let alone SCM-based project management cloud-software), and even a large improvement over the days of CVS, SubVersion, and SourceForge.

Well of course, yeah, there's their value creation. What I don't see is how they capture some of that value as profits.