Are you sure you're dealing with melamine? I've never seen the stuff wear through. Chip near the edges, yes. Scratch? Occasionally. Wear through? I, personally haven't seen it. And I've abused the crap out of my desk! I used it to make airplane models for years and regularly scraped glue off of it with a razor blade. It has a few scratches here and there, but otherwise looks great.
Yes, countertop laminate is more durable than melamine. Hopefully, you won't need to chop vegetables or drop 400-degree pans on your cabinet, though. Countertop laminate is really overkill for an arcade machine; it's designed for a much harsher environment.
FYI, melamine itself is a plastic, which is waterproof. The bare particleboard edges, of course, aren't waterproof unless sealed. I caulked the joints in my reptile cages and haven't had any problems. Applying edge-banding to the edge can also help prevent water-absorbtion and swelling, but isn't fool-proof.