Can I know where's the "regulation" role in this matter?

Having regulation doesn't automatically mean it won't fail or it's legit, take example with stock.

It's easy for any company to run IPO, they only need to create a company without need to build a physical building, having specific minimum amount, having few shareholders etc. They meet all the requirements, run it, after many people buy their stock, they can exit and make their company suffer loss and then bankrupt.

Which mean, having regulation won't make cryptocurrencies are safe.