I understand what you are talking about. such cases are really a lot. Because of such dishonest people all over the world, most people are suspicious of cryptocurrencies. But not all projects are deceivers and fraudsters. There are many truly promising and decent projects.
Unfortunately, due to various kinds of fraudsters and scammers, there is no trust in the majority of users in the world for cryptocurrencies. Only those who have been engaged in this issue for a long time are able to separate truly promising projects from all the crap that fraudsters offer.