I'm sure this has been discussed on BFTB before and certainly elsewhere, but here's my take on it.
1. Nostalgia - Something you had as a kid and want it back again.
For me, when i decided to get into collecting 'proper' around 1997 I drew up a list of figure names I remembered from my own childhood. AF Blowtorch
was top of the list, then AF Flash 
the more I looked into it the more I wanted to get everything I had back again. I'm still going!2. You never had it before but wanted it 'back in the day' and now you can buy it!
For me this is something like a Roboskull. Didn't have one when I was a kid but now, aged 37, I need one!!
3. You didn't want it 'back in the day' but man...! It's so cool to you now!
You've spent time on BFTB and if you weren't before, you are now converted to the greatness of Palitoy! So, your intentions towards collecting alter.
As a kid I would go for the articulated GI Joe style figures everytime, but since being on BFTB I've formed a deep love for the earlier Palitoy figures. I suppose I'm saying this is a trend in collecting based on something old becoming something new for you.
4. Completists
There's a certain drive I think in really wanting to complete a wave, or a group of figures. Many on this forum have achieved very specific collecting goals of completing wave one, or all the Q Force, Z Force etc. For me, I'm a sucker for sub teams too. If I discover I have three characters that were originally part of a sub team of six, there is nothing on earth that will stop me hunting down the remaining figures!! It may take me a decade, but I'll complete a sub team or die!!
5. The X Factor - No, not the crappy TV talent show!
I mean the combination of design, colour scheme, characterisation and undefinable appeal of some action figures that just jump out at you as a must have.
For me I set out to only collect Action Force and GI Joe up to 1988 as that's the last year I actually bought any figures as a twelve year old kid. Then I saw Bullhorn (1990) on eBay and had to have him!! That led me onto other figures in later years and I don't even know how many I have now.
I'm sure there's more to it than this, just what's in my mind tonight
and I blame the time and economy. I have way too much going on at work and trying to divide my time between work and family is always tricky. That leaves very few hours a week or even months to do anything serious about the collection. I get a lot of new stuff but rarely have time to photograph it for my site or even as a collection update on here. My latest "mammoth" task is going to be a move of my entire collection to a new room, this time with more shelf space and better layout for proper display of my larger vehicles (Defiant, Flagg and 3 Terror Dromes). Add to that a financial situation where every penny has to be turned every quarter after most utility companies and morgage payments have been gathered instead of spread across the year. I know it makes their life easier but its also a pain when it happens from one quarter to another (hard to balance the budget). I still want to have a "play"-account for those odd "this-is-too-cheap-to-pass" deals but since I cant get myself to sell anything from the army building its hard to keep that account going. I tried to sell a few nice pieces but shipping costs have killed every attempt so right now I am just accumulating more and more that really needs to go............just glad that my collection still brings me joy or I fear that it would simply be sold off as we have seen numerous times lately.
