Whether or not digital currency is worth investing in, I think, depends on one's level of confidence. Because, investing in cryptocurrencies has a greater risk than investing outside of crypto.
Again I say, worth it or not, it depends on one's will.
Investing in digital currency is a smart choice for someone, apart from being able to monitor the market movements of investing in currency, we are the ones who manage it ourselves. Therefore, I think your statement is not correct. investing in digital currencies has little risk if one is not smart in analyzing and reading market charts.
He generalized his statement too much, but the point he is trying to explain is probably that the stock market with real companies backing the stock is a safer investment in that there isn't all too much you have to do if you invest in companies like Amazon or Google. Well established companies with dividends and a proven track record. In crypto that is indeed quite a bit different as things can turn around very quickly. Just take the crash of this year as an example. You wouldn't really have to expect that to happen when you buy Amazon or Google stocks, but with crypto that is possible anytime.