Actually particle collisions at energies orders of magnitude higher than the biggest particle accelerator anyone has even seriously thought about building have been going on since long before humanity was around. Cosmic rays^[1] with energies fantastically higher than anything that a particle accelerator can produce have been recorded (eg the Oh-My-God Particle) so any event that will take place in a collider is virtually certain to have taken place thousands of times naturally by now.

Also how is science supposed to advance if not by doing things that have never been done before? Even potentially dangerous things, if everything with a significant risk was disallowed then there wouldn't be much left for anyone to do.

[1] Which do include particles of every type known to man (and probably some that aren't yet), blame the same people who refer to everything with an atomic mass higher than helium as "metals" for the name (ie astronomers)