It's interesting to me both to observe, and to note that somehow no one has yet mentioned, how this argument seems to correlate to contemporary political/philosophical attitudes.
There's the conservative point of view: human nature is inherently greedy, self-serving, and antagonistic; given the opportunity people will be lazy or be dicks; a market economy based on trading labor for survival is the only real way to motivate people; if everyone seems cooperative it's probably because of some sinister oppressive government.
And then there's the liberal point of view: human nature is inherently creative and cooperative; given the opportunity people will find ways to rise to their greatest personal potential; real motivation is intrinsic rather than extrinsic; government exists to serve people's needs, not to control them.
Star Trek is clearly based on the latter set of ideas and principles. To me, those seem both a far better
and a far more
realistic portrayal of human psychology and behavior. Those with the opposite worldview, though, will almost unavoidably see Trek as implausibly utopian.
Keep in mind, pretty much all of human history to date, and the economic systems we've built during same, are based around the concept of
scarcity. Both basic resources, and the goods we create from them, exist in limited (often nonrenewable) quantities and take a great deal of time and effort both to create or acquire, and to distribute.
(Of course, those same economic systems rely on the obviously incompatible assumption that "growth" can continue indefinitely... but I digress.)
What we're talking about in Trek, though, as others have mentioned, is a
post-scarcity economy. Not necessarily the same kind as posited in a lot of contemporary SF and futurist speculation (i.e., post-singularity, nanotech-based, etc.)... but still, the basic idea is similar. Energy is clean, limitless, and so cheap as to be virtually free. Using that energy, matter is easily converted from one form to another, and instantly transported from one place to another.
A post-scarcity economy may be hard to imagine, because all our intuitions are built around being raised and acculturated in the opposite, but that's what this exercise requires. Our modern vision of how "markets" operate (whether for goods, or for labor) relies intrinsically on scarcity. In Trek's future, that vision is obsolete.
To clarify: saying that money doesn't exist on Earth doesn't mean that
personal property and possessions don't exist. Neither Picard nor anyone else ever made that claim. Moreover, saying that money doesn't exist on Earth doesn't mean that money doesn't exist
elsewhere in the galaxy, to facilitate trade amongst different cultures with different systems and different values. No one ever claimed that either.
How do all the details of a post-scarcity economy work? That's not clear, nor does it have to be for story purposes. But what it does clearly mean is that people's basic motivations and behaviors will be different. What the conservative cynics think of as "human nature" is no more than a situational social construct, one that will no longer apply. Others have already mentioned Maslow's hierarchy of needs, a concept supported by tons of psychological research. When a given level of that hierarchy is met (e.g., basic physical and emotional needs), people shift their attention to the next level up (e.g., self-actualization).
Imagine: your basic needs for food, clothing, shelter, education, health, and entertainment are guaranteed. The scut work (sewage treatment, or what-have-you) is handled by automation. All the information in the galaxy is at the tips of your fingers, and you can go anywhere you want to go at the speed of warp drive. What do you choose to do?
You can be an artist. Or a teacher. Or a chef. Or an architect. Or a writer. Or a public servant. Or whatever floats your boat. Others aren't necessarily obliged to pay attention to you, of course, but if you're good at what you do, you'll
attract attention. (It's like the economy of the internet — all of this stuff we do for free! — expanded to the real world.)
Of course, some things are still unavoidably limited (if not necessarily scarce
per se). If you want a beach house in California... well, there's only so much of that real estate to go around. But if it's really
that important to you, you can probably find something from your own skillset to barter to the current owner of one to motivate him/her to trade it to you.
Or if you have an urge to explore the frontier? You can join up with a colony mission, and help design your own social contract from scratch on another world. Or you can join Starfleet... and be trained to develop your own skills and talents to their peak, and have the opportunity to explore strange new worlds, to seek out new life and new civilizations, and to boldly go where no man has gone before.
But hey, you wouldn't be drawing a
salary! So what's the point, eh?
But seriously, as this thread has already made clear, any number of people would be more than happy to seize that opportunity. And those who still sincerely ask "what's the point?"... are simply missing the point.