Tech stocks are assets, but Buffett has always said he purposely avoids most of them because he doesn't understand them well enough. Taking him at his own word, we shouldn't put all that much weight on his cryptocurrency opinions.
Here[1] are the signs of asset bubbles. I've posted the signs I feel are most relevant to Bitcoin below.
> Rationalizing borrowing, lending and purchase decisions based on expected future price increases rather than the ability of the borrower to repay.
> Rationalizing asset prices by increasingly weaker arguments, such as "this time it's different" or "housing prices only go up."
> A high presence of marketing or media coverage related to the asset.
[1] https://en.wikipedia.org/wiki/Economic_bubble#Identifying_as...
I know people hate to hear this but unless you have a target price and a rational explanation as to why it's worth that much you're just gambling.
EDIT: More specifically anything with as much hype as crypto (and tech to a lesser extent) is not really in the value investing camp in which Buffet is trading. Avoiding them entirely is a very useful heuristic for him.
[0] http://fortune.com/2017/05/06/warren-buffett-berkshire-hatha...
He is a major investor in Apple and was a relatively-early backer of BYD, the Chinese battery technology company.
[1] https://www.cnbc.com/2017/02/27/billionaire-warren-buffett-m...
[2] http://money.cnn.com/2017/10/11/investing/byd-warren-buffett...
That goes to show that he's aware of the limits of his expertise, and clearly he has an opinion on bitcoin, so presumably he considers them within his range of expertise.
- I don't understand thing ABC, therefore I won't form an opinion on it (true fact, by his own admission... conservative and reasonable).
- Thing XYZ is generally acknowledged to be more complex and harder to understand than ABC (debatable, but I'd love to see someone show me how crypto is easier to understand than Google/Facebook/Amazon/Uber/etc.).
- Even though I don't understand ABC and won't form an opinion on it, I will form an opinion on XYZ which I understand even less (... wut? Why would anyone put stock in this statement, given the prior two statements?).