I know how you feel, it can become an obsession if you aren't careful.
I found myself in a situation a while back where I wasn't even playing music but collecting all the Freeware VST's. At first I thought of the VST's : "Wow! These are free I might use them later on so I need to get everything I can while it's free". I ended up with 2 out of 100 or so Freeware VST's that I kept that I might use.
Your Daw can be compared to your house in a way, I mean you keep things laying around thinking you might use them later and end up with a bunch of clutter keeping you from actually using what you need to in the end.
While I know you are speaking of purchased VST's/VSTI's. Look at it like this would be my advice : "What's the point of buying anything new if you haven't spent time using what you have already got to begin with?".
I recently upgraded to Sonar Pro and for me it pretty much has everything I need. I mostly record basic songs, bass/drums/guitar/every now and then a simple keyboard part. Although I do plan on upgrading the TH3 Overloud Full version guitar VST.
When I was using Music Creator's various versions before upgrading I often found myself downloading freeware stuff and checking out the purchasing vst sites day dream.
My advice would be like I said : "Take the time to use the ones you have first before considering buying anything else, chances are you already have what you need but you just aren't aware of it".
A lot of times too much of a good thing is too much, it can clutter things and make you more confused than creative.
Just my opinion. I wish you luck! I know how you feel.