This is easily said, but remember you're talking about a security-sensitive application. Do you really trust yourself to keep your fork secure? I know it doesn't look like it on the surface, but password managers have become wickedly complex, especially if you require things such as shared vaults, audit logs, a zero-knowledge architecture etc. The reality is maintaining your own fork won't be feasible for the vast majority of users, even those with a technical background.
> Why should I trust you (and a product I've only just learned about)?
The simple answer is that you shouldn't. You should ALWAYS be sceptical, and look for possible indicators of a company heading down the path to the dark side. Like taking a 9-figure sum of VC money for example ;)