Mac kind of sucks, because of this and many other reasons. This happens for Windows as well.
The fix is to download the .jar of the launcher and run that.
See, the MAC app or .exe tries to connect to the internet, but it can't (no internet!) so it crashes because it went into an unexpected error. Only in Windows, it's programmed to connect, and if there is no update to run the .jar in your %appdata%\.techniclauncher folder, and it does that eventually, it takes the app a while to crash. Mac, on the other hand, crashes immediately but doesn't do anything else.