Lots of good points have been made already. There are a variety of levels of a "charteryacht." You can run an operation like Capt. Ron on a wing and a prayer, with a lot of deferred maintenance waiting to haunt you, and you'll still find customers who want to get out on the water for as few little dollars as possible. Those people are more concerned with what it costs per person, rather than the vacation or experience they are buying.
On the other end of that spectrum, you can run a high dollar luxury charteryacht business, and you'll find customers for that, too, but you have to really WANT to be in the hospitality business and have some degree passion for what the work really is - it's not the "marine business". It's not the same as spending the day on your boat with your friends. It's hard, long days of being nice, polite, and smiling even when you don't want to.
In the current financial climate, it is this kind of activity that gets cut out of a family's budget first. You likely won't get wealthy doing day charters, but if it makes you happy to get more time out on your boat with someone else footing the cost, then there is a reason to do it. For me, I very much enjoy getting up early, cooking nice meals all day and doing my best to ensure guests are enjoying themselves and the boat and have everything they need.
As for more effort in keeping up the boat, I have to say that if I didn't charter, I would still keep my boat in the condition she is in now, and no, she's still not perfect. I strive to be as good to her as I possibly can, constantly making improvements to her, regardless of whether there is charter business lurking or whether I'm just a liveaboard - I like nice things and to live in a nice, clean, tidy environment. I've been described as "being married to my boat" because I am always working on something that makes her a little nicer. If I wasn't trying to charter her, I would not change a thing about the manner in which I keep her.