To answer the OP, it's a mix of reasons for me as to why I chase them. Certainly, I don't need to fly anywhere, I could just stay at home. But I have a passion for air travel, so when sales come up I do like to take advantage, I also have a passion for travel and seeing new places. I like to go to the places most others usually avoid, the outback, small towns etc.
Being a member of this site I've met quite a few other members, and this has brought me out of my shell and helped me socialise, though socialising usually happens in a lounge.
Obviously, I'd prefer not to sit in the terminal, travel tends to feel luxurious, even in economy, so lounge access needs to be earned (or bought). Then I can also socialise.
Finally, I may not always travel a lot, but in the future when I'm not travelling so much I'd like to still have lounge access. I could probably buy it at the time, but earning LTG would also be a way forward. Seems like an absurd goal, but would make later life a bit easier when travelling.