I think Trump is probably right about this. It is well known that there has been systematic voter fraud in Democratic strongholds going back to the 19th century; the big city machines in New York City, Chicago, Philadelphia, Detroit, etc. Wherever organized crime or "community organizers" have a heavy presence. Or, millions of illegal aliens. Trump may be stirring up a hornets nest on this one, but if he wants to drain the swamp...
As someone who regularly uses voter databases for work across multiple states (which are PUBLIC RECORD), this is totally nonsense. Dude, 1-in-30 Clinton votes would have to be illegal (assuming that no illegal votes are for Trump). That's incredibly ridiculous and you're ridiculous for claiming he's "probably right." I get that not everyone has close familiarity with the registration and voting systems...but if you don't understand how our electoral system works, please, please research and discuss it before making claims like this.