I have to say, I'm kind of impressed that you're even still considering this project, given the feedback you've received!
I do think it will cost more than you anticipate just to get this boat in shape to sit at a dock so you can chill and hang out. (I also think that will get pretty boring very quickly.) I also wonder if you've looked into where you might dock this boat and how much that might cost? I trailer my boat, but I imagine the cost of a wet slip could be substantial.
I replaced the transom, floor and flotation foam in my much-smaller boat, and it still took several hundred hours and cost several thousand dollars (and I already had many of the tools needed for job).
If you're looking for a project boat, you can find many that are much more reasonable for a first-timer to take on, and your net investment will be a lot less.