This one gets multiple categories because I thought of this just after giving up in disgust with reading Smyth posts, but it applies generally. It is somewhat of an aphorism which probably is not entirely original to me. Somebody I read may have said this flat-out, maybe Robert Pirsig or Richard Bach or somebody of their ilk.

When you say you'll do something in the future, or something will happen in the future, what you really mean is that it is not happening now.

Partially inspired by the following passage from All Families Are Psychotic, Douglas Coupland: "The biggest change is that I stopped believing in the future . . . as being a place, like Paris or Australia - a place you can go to." Neither my pseudo-aphorism nor the Coupland segment should require further explanation in this context.
And while I'm quoting authors in a probably vain attempt to seem well-read, another brief passage which seems relevant, from Cryptonomicon by Neal Stephenson:

Arguing with anonymous strangers on the Internet is a sucker's game because they almost always turn out to be - or to be indistinguishable from - self-righteous sixteen year olds possessing infinite amounts of free time.

This itself seems inspired by "Never argue with an idiot, somebody watching may not be able to tell the difference between him and you." (And I'm sure Robert Heinlein said something more quotable along those lines, probably in The Moon is a Harsh Mistress or The Notebooks of Lazarus Long.)