Plan so you can live comfortably, then with the excess, fund people doing things you consider important, if they're open to contributions. Sponsor schools and community stuff.

Accumulation of wealth beyond the reasonable needs of yourself and dependents is pointless.

Full disclosure I don't have the income for this yet so I can't offer experience just opinion.

But what about early retirement?

I don't want to work until I'm 65. I'd rather work hard now, and be aggressive or "greedy" about my salary, so that I can retire earlier and fund things for my future family. That's the point of accumulation of wealth.

I think you need to be realistic about what "early retirement" means. To a lot of people this just means spending their time not at a desk job. Instead they spend their time making money (maybe less money but still some) in different ways. Ways they find more pleasurable. If that's the case you don't need to save all the money you'll ever need for the rest of your life by the time you're 50 because you're not spending your remaining 50 years doing literally nothing.

Just be honest about when you've accumulated enough, I guess. If you're already sitting on a large enough pile of savings to live comfortably until you're 120 maybe it's time to retire / give back, not buy extra property.

What kind of data are we talking about here?

I'm sure there are all kinds of metrics and analytics available but I'm interested:

  What are the "rawest" forms of user interaction that Facebook makes available to these companies?

I'm not in the business of using this data and neither I suspect are most of the Guardian readership so it would be nice to see this elucidated.