Well, I want people to read my comic - if there's nobody reading, I'm just shouting into the void - and the more people the better, you know?
I'm closing in on 4000 subscribers, and I value every single one of them. I realise that not all of them are actively reading my comic, I realise a bunch of them will eventually wander off and unsubscribe, and I know that not all 4000 of them have my comic as their very favourite comic - but I appreciate every single one of them. I will never NOT be overjoyed to know that one more person is enjoying what I do.
Yeah, I haven't hit this point, and I doubt I ever will. I've spent over a decade on the internet, posting my art and getting hardly anything but crickets chirping in return - I kept going then, for the love of storytelling, and I am definitely going to keep going now, for the same reason.
One reason so many of us are focused on subscribers is because a lot of us are signed up to the ad revenue program, and more subscribers means we earn more money - an in webcomics, every cent counts. Not every subscriber will be contributing towards that - some of them read with ad-block on - but every little bit helps.
But like @shazzbaa said - I don't think I've ever seen the whole popularity-will-breed-subscriber-obsession thing you're talking about. I've seen a couple of creators get stressed by having so many readers, and feeling the urge to work faster and thus burn themselves out, but that's never been about gaining more subscribers - it's always been about living up to the expectations/demands from the audience you already have. But that's a whole separate issue, you know?