Trust come from reputation. There are some legendary members with no reputation within the sphere of project management, bounty management, community management etc. Others may even have negative trust on the forum. I will only trust a legendary member who announces a project if the member meets all of the above.
Yes, and each person's beliefs are clearly different, just like you who will only trust the legendary member who announces the project if the member fulfills all the things you say, but what you should know is that there are also members who are not legendary but he has a good reputation for everyone to trust.