Security matters if your concern is the data leaking to a potential malicious actor. The concern that I'm speaking to is the intended use of the data. Google is definitely going to use it for ad targeting and building a "shadow profile", but a small developer probably won't. This one says they won't, but even if they do they're likely to be much less effective than Google would be.
Having a random developer create a shadow profile isn't the same.
The scale is vastly different and can be used to track you from site to site.
I can’t say I love having Google track me, but I don’t feel any better about someone else doing it either.
Why is Google security better than anyone else? Monopolies often have more resource, but lack motive, because they are a monopoly. Without transparency we have no idea how secure Google's systems are, but we do know Google has been hacked before.
Also, Google knows how to make profiles and it knows the importance of that data amd keeping it safe. It is also somewhat answerable to Consumer groups,users,shareholders,regulatory bodies. Indie dev doesn't know how to make good profile, more likely to sell the data to make revenue. Not ridiculing indie devs, just ridiculing your assumptions that if a solo dev is an angel.
https://www.labnol.org/internet/sold-chrome-extension/28377/