When Mystery Inc. destroyed the Evil Entity the universe was altered, creating a town that was unaffected by its influence and thus having no need to make a museum for all the strange phenomena and fake monsters terrorizing Crystal Cove.
Scooby-Doo! Mystery Incorporated
The gang went there to get information about aliens.
When the Evil Entity was destroyed, it altered reality for all of Crystal Cove; meaning there was nothing to make profit from. There was no sign above the front door, implying the museum was just a regular shop.
- Scooby-Doo! Mystery Incorporated