Trust is built over time and for a project to be seen to be trustworthy and reliable, they have to be present in the industry for a long period of time and consistently keep the community aware of their developments. The community needs to be aware that the project is still in existence and they need to be concerned about the interest of the investors and token holders.
An ideal situation and indeed most altcoin projects will fail to tick those boxes. Bitcoin itself does not have a very public team but the concept has been supported by the community and therefore it has become so popular among netizens. Altcoins try to copy that fame and that leads to infamy and hype eventually collapse of the project because the core development is lacking.
Growing community is often lacking as well because the short term gains via pump and dump attract more investors than long term holding.