Space hasn't really been an issue for me until the last several years. I was more of a casual figure buyer up until ROTS came out when I started working, had additional income, etc. I basically had a desk and a dresser to put stuff on (everything was in my room as I lived with my parents) so in 2007 we put up some shelves on two walls in my room. One side hosted LEGO and the other side hosted Hasbro figs. I had plenty of room! Then I started buying Indiana Jones figs, Marvel Universe figs, and 99 percent of the Star Wars offerings and things got out of hand again. I started buying LEGO again after a several year hiatus in 2011, and that's when I completely ran out of room. Since then, my figures have remained boxed and inside of my closet. Most LEGO sets I buy I keep boxed as well, mainly due to a lack of space for them. I even disassembled a lot of older sets and put those in the attic, and still have little room for it all.
One problem I have is I could easily store some stuff since I've been out of my parents' place for a year but my closet is filled with the aforementioned carded figures from the last 3 years, along with several Rubbermaid bins full of old 90s toys (Marvel/DC Animated figs, Power Rangers, WWF, etc.). I've considered getting rid of the old 90s toys but I don't want to deal with selling them online and definitely don't want to just give them away. There's a new store in town that buys vintage toys but I'm assuming they'd only be interested in a handful of items.