I suspect most of his critics are the sort of folks who think that they would be billionaires if only their taxes were low enough and governments weren't so restrictive about things like labor laws and environmental regulations.
He's only one among many such types penning editorials for NYT.
When he sticks to economics (his blog has a higher percentage of economic material compared to his column) he is definitely worth reading and shouldn't be dismissed with ad hominem attacks.
He doesn't always give the best advice...
Had there not been CDO's threatening to take down the world economy, the credit drying up in 2008 would have been far less severe.
That said, I believe he's describing, not advising
Bitcoin could literally be a trillion dollar a year technology. Ten years from now there could be a trillion dollars a year of transactions flowing through servers running the exact same software that is running today.
This could be true AND it could simultaneously be true that all Bitcoins currently in existence are worth $0. Why? Someone could take the exact same technology, and start a competing "coin" -- the way dozens of people already have -- and if one of those manages to win, then the "original" Bitcoins are worthless.
The technology could succeed while the currency fails.