Yes, DW and I have added on twice (at AKV, and at OKW) and we still haven't stayed at our first "home resort" of SSR (although we do have a stay booked for next February). The AKV addon was a small addon to our first contract at SSR, but the OKW purchase was a new master contract so that we could have our grown kids on as full owners rather than "associates".
And you're right about it being a sickness -- here's how it goes:
Yes, indeed it is a sickness!
The first symptom is the euphoria of being a
DVC owner.
But this is shortly followed by the obsession stage, where you may find yourself:
Frequenting internet forums dedicated to DVC.
Constantly pouring over
point charts for the various DVC resorts.
Planning not only your next DVC vacation, but your next 3-4 vacations!
Then comes the depression stage, where you wonder why you didn't buy more points?

And you begin to ask why things like work and school should get in the way of your Disney Vacation.
This moves into full-blown "addonitis". It may start as just a small addon contract at AKL or VWL

but quickly may move into wanting to accumulate contracts at ALL the DVC resorts, so as not to miss out on any 11-month booking window!
At this point, there is no hope for you.
But then, there will be lots of joy!
So just go with it; have fun. And, Welcome Home!