It's more than one thing. There are lots of different people involved with a mixture of motivations. It's not just playing out in a single forum, either.
And while I'd agree making a "quick buck" is a driving factor, arguably "the" driving factor, that term is also relative. The average time between trades for a high-frequency trading investment firm is 40 seconds. It's out-of-place to talk about these folks making a quick buck when average trade times are measured in seconds and money is made based on having a PHYSICAL location that enables faster trades by nanoseconds.