Why couldn't it have been done 2 years ago, and why will 2 years in the future be too late?

You'll get more support on a hard, important, project than a derivative one.

Most founders have not managed people before, and they certainly haven't managed managers.

The idea should come first, the startup should come second.

If you ever take your foot off the gas pedal, things will spiral out of control, snowball downwards.

There are exceptions of course, but most companies start with a great idea - not a pivot.

You want an idea that not many other people are working on, and it's okay if it doesn't sound big at first.