You TCO is negative in all cases. Because you had something that was working enough, otherwise you would have changed it. But now you need to spend money to change. Even if for a good price.

Also you have to take into account that you pay but not have 2 working devices in the end (old and new). Just one.

Sure, if the new one was providing significant value, there could have been an interest. Like if you network was saturated. But that would be surprising because currently 8/10 years old ac wifi routers are more than enough for most households usage.

Also, what is interesting is the Stockholm syndrom: some comments here are saying that it was probably old enough to be changed, so not so bad. But in that case, did you think about that, that you would probably have to change your router for a new one before receiving the obsolescence notice from Google?