Alright, Hear me Out

If you could somehow get everyone in the world, right now, into an enforcable contract to A) drop all other human productivity and begin research on a time machine, and B) travel back to the moment after the agreement was signed as soon as the time machine was completed, wouldn't that look the same as basically wishing something into existence? Is the failure of a time machine to visit us proof that it can't be done, or is it reflective of a Temporal Prime Directive that the inventor of the time machine adopted after developing his terrible, terrible creation?

My office doesn't have windows.