Why Nobody Came to the Time-Travelers' Convention
No, the real reason is simply this: no time travelers came because no time travelers came. Think about it. Since nobody from the future showed up, this event will fade from the public mind quite quickly. Perhaps it might warrant a couple kilobytes on archive.org's Wayback machine. In any case, it will be forgotten long before anyone invents a time machine. Thus, anyone with a time machine won't know about it and therefore won't travel back to attend. Simple, even though causally it's rife with paradox. What is needed in order to get time travelers to come to an event is a way of marking its location in time and space that will endure for longer than a website. Engraved in stone? Maybe. Carved in huge letters in the surface of the moon using a laser? Possibly. How about you store it in something that's already lasted thousands of years, and is likely to last a few thousand more - like the pyramids of Egypt. A wall on the inside of one of the great pyramids would be a perfect place to put the coordinates of a time travelers' convention. In fact, it's surprising to note that there isn't intertemporal graffiti all over historic landmarks like the pyramids. If I had a time machine, I wouldn't think twice about carving my initials into one of those huge limestone bricks. "K.B. was here; June 9, 3392 BC". Perhaps it's there, just not in an accessable place. We'll need to dismantle the pyramids to know for sure.
In the meantime, we'd better busy ourselves with the practical aspects of constructing a time machine. Either that or (and this is almost more likely) improve our space-faring capabilities so we have a better chance of finding a time machine left by some ancient civilization on another planet... yes, Window of Opportunity is one of my favourite Stargate episodes. Of course the last few episodes of season 8 featured a time machine as well.
Now if only I could find something of infinite mass...