The unstated assumption appears to be that doing any single thing can be highly parallelized and the window of opportunity is infinite. But reality is rarely that kind.
(1) Some things take 40 years of consistent mid-level effort. Even if you could quadruple your effort on it, it wouldn't get you there in 10 years. Building a family, for instance.
(2) The chronological window. We live in a unique time in history (as have people in every other time). It's an incredible time to be a web developer, for instance. Ten years from now I doubt there will be as many opportunities. In the 1950's, you had amazing opportunities at being a worker in heavy industry; in the 1960's you could play a valorized role in the space race. Nowadays neither is an option.
(3) Age window. Different ages lend themselves to different things. Sure, people in their sixties can run a marathon, but it's a hell of a lot easier to do it in your twenties. And unfortunately many of the things we might want to do are early on in life--people's career paths are fairly set by 30, and we've passed our physical peaks by 30. These aren't hard and fast rules, but they're both very real tendencies that you've got to account for in managing your life plans.
(4) Some things actively conflict in more than just competing for your time and dedication. It's impossible to have an undergraduate experience that is both set in a large Southern state university centered around sports and a small private liberal arts college in New England.
Multitasking to the point of constant stress can lead only to disaster, of course. The solution isn't to pretend that you'll eventually get to do everything you want but instead to choose carefully what you want most and then do it well.
I'd like to expand more on (2), timing is incredibly important for technology-based ideas. An idea that is ahead of its time or too late could fail just for that reason.
Let's recount the numerous attempts at tablet computing since the Newton in the early 90s to the iPad just a couple of years ago. Timing and the state of technology in time is important.
Sometimes a new technology comes around and threatens to disrupt everything, like Bitcoin. If you have an amazing idea that capitalizes on this momentum, now is the time to execute—not 10 years from now when the Bitcoin economy has been banned and destroyed or matured and stabilized (one can dream). This is the same way that mobile applications were an incredible opportunity in the iPhone age of Smart Phones, but much less so today.
Ask yourself: What is the ideal time window for your idea? Though some ideas are always good, given the right uncompetitive conditions.
But this is quite the opposite of long-term thinking.
(Except, maybe, in the startup world, where long-term often seems to mean, "next year".)
Focusing on just one thing at a time for a few years means leaving it entirely behind when you're done with it; it means not thinking about other things in the meantime; it means ignoring the possibility that, in 10 years' time, the three projects that you're juggling simultaneously could tie together in a really neat (and maybe profitable) way.
Maybe some people are doing lots of things at once because they feel like they have to hurry, and that could indicate really short-term thinking; but slowing down to a rate of one thing every few years is, at best, near-term thinking.
I've spent the last three years building a really tiny business because, one day, I intend to build an empire.
Sometimes that's not the case, and you simply have to give up on one to pursue another.
I've been trying to push the related "you can have everything you want to have, just not all at once" ideology into my subconscious. It's still so easy to forget. Projects get dropped for more exciting ones. And I know you have to keep telling yourself to just hold off and be patient.
This is a great reminder, very well written.
How can you focus on one single thing when you want to do them all and when you see that everything is connected and you don't have the necessary experience yet?
I've ended up in an infinite loop. Jumping from task to task. Help - I need a breakpoint.
I've got more ideas and interests I want to pursue _right now_ than I have time in the day. I also can't imagine going back to being an employee after having this realisation!