First of all, economics is not a uniform discipline, and not all economists are Keynesians, for example, see the Austrian business cycle theory or /r/Austrian. Recently in Forbes Jon Matonis wrote a piece called Fear Not Deflation. Although I'm sure that would be heresy to many economists.
Satoshi Nakomoto said Bitcoin is "completely decentralized, with no central server or trusted parties, because everything is based on crypto proof instead of trust. The root problem with conventional currency is all the trust that’s required to make it work. The central bank must be trusted not to debase the currency, but the history of fiat currencies is full of breaches of that trust. Banks must be trusted to hold our money and transfer it electronically, but they lend it out in waves of credit bubbles with barely a fraction in reserve. We have to trust them with our privacy, trust them not to let identity thieves drain our accounts… With e-currency based on cryptographic proof, without the need to trust a third party middleman, money can be secure and transactions effortless."
Nakotomo began writing Bitcoin in May 2007, based in part on Nick Szabo's Bitgold proposal. He apparently was not a fan of central banks printing as much money as they want, leading to inflation, and debasing the currency. Or a fan of fractional reserve banking, which can lead to bank runs, and credit bubbles, and banks collapsing. Japan's bubble economy from 1986 to 1991 collapsed, and the collapse of stock prices and the real estate bubble happened gradually and lasted over a decade (some have said two decades). Banks in Japan needed bailouts because they invested in real estate and the bubble popped. A similar thing happened in the US. Investment banks like Lehman Brothers invested in housing related assets, and were leveraged 31:1 by 2007. With the subprime mortgage crisis, Lehman lost billions of dollars and collapsed in September 2008, with the largest bankruptcy in US history, leading to a global financial crisis.
Four months later the Bitcoin network came online (and mentioned a bank bailout in the first ever block). I mean, the idea that banks can be trusted with people's money has been eroded again and again.
But the concept of untraceable electronic cash goes back to at least 1985 or 1988. The cryptographer David Chaum founded DigiCash in 1990, but it never took off because it needed banks for the system to work (to declare coins as valid), and those alliances never panned out (it's also been said that David Chaum was too far ahead of his time).
On the other hand, Bitcoin is a cryptocurrency that does away with banks (which might eventually want bailouts, or wreck a country's economy or the global economy with reckless speculation in real estate). If a bank says they're too big to fail, Bitcoin says "we don't need you in the first place."
Personally, I think "Satoshi" would like to protect his/their identity (and I do have my own ideas of who he might be). Satoshi may have certainly foreseen the possibility of becoming rich by writing Bitcoin, but that would be no more a "scam" than Mark Zuckerberg writing Facebook and making it a public company and selling shares. Yes, early adopters of Bitcoin make more money, but people who believed in Google or Apple or Microsoft early on made more money too.
/u/gwern wrote "It may be that Bitcoin's greatest virtue is not its deflation, nor its microtransactions, but its viral distributed nature." Bitcoin is peer-to-peer electronic cash. Not only is the blockchain distributed virally, but bitcoin's adoption also spreads virally (and Nakomoto created an incentive within the protocol itself for it to do so).
Bitcoin is the first working cryptocurrency that has been valued at over $2 billion. There will eventually be a little under 21 million of them (or 2.1 quadrillion satoshis). Various "altcoins" or alternative cryptocurrencies based on bitcoin have different sizes of the money supply (for example there will eventually be 84 million Litecoin, and 100 million Freicoin, and I believe that PPCoin and Liquidcoin have no limits). But I'm more inclined to believe that many of those are scams. And I don't think any of them have configurable inflationary mechanisms built into their protocol.
Anything that can be traded on the open market is prone to instability, because people are fickle and prone to herd behavior and not entirely rational. But a higher value would arguably make BTC more stable. (For example, one share of Berkshire Hathaway Inc, BRK-A, is worth $160,525 on the NYSE, and has a market cap of $264.22 billion. That's probably not going to change a big percentage during the day.). Every BTC that exists is currently worth $1.16 billion. If 1 BTC is eventually worth $10,000, then 0.0001 BTC will be worth $1. If 1 BTC changes during the day, to $10,050 or $10,900, then 0.0001 BTC will still be worth about a $1. But 1 BTC is not there yet. On the cryptography mailing in January 2009, Hal Finney imagined that if Bitcoin becomes the dominant payment system throughout the world, then 1 BTC might be worth $10 million. (I think the Winklevoss twins currently have 110,000 BTC or so, and if it ever does hit $10M/BTC, they'd be worth $1.1 trillion.)