If you are the sole person responsible for the main feature of a startup, and it isn't completed, you know that the only thing you can do is put every hour you have into it to try and make it work.
> you know that the only thing you can do is put every hour you have into it to try and make it work
This, of course, illustrates, why it's difficult: when one knows something that happens to be false.
That's why it's important to have these kinds of discussions here, even they appear to surface concepts that may seem obvious to some people. To other people, it's important to read/hear that perspective, lest "tunnel vision" or an "echo chamber" takes hold.
That is what is so hard.