Earlier quoted context omitted.
A better question might be: How is anything an investment? If the stock market is priced efficiently, it is as much a gamble as Bitcoin. The stock market is of course not perfectly efficient, but it is likely extremely efficient relative to the knowledge of your average retail investor. Which means that buying Bitcoin or other cryptos is no more a gamble than any stock market investment with a similar volatility.
I also think the stock market is not "investing" but think it's safer to invest. 1. There's more government regulation and less manipulation. 2. New money is constantly flowing in, via 401K's and pensions. Most people aren't even aware they're invested in the stock market. 3. The government cares so much about the stock market doing good. Look at how Trump brags about the booming market. If it goes in a funk, the gov…
Well, you're leaving out something something about the company putting your money to use to increase efficiency or output something something and something something about dividends from the proceeds, none of which you have with cryptocurrencies. (Though it may be disputable whether those are truly the reasons behind the historical returns of stocks and thus good reasons to expect it to continue, even if you wouldn't guarantee the exact numbers, or if those are simply motivated reasons that may or may not be reliable future indicators...)