He is very pessimistic person. He must say "I am holding 90% of my net worth in digital currencies such as Bitcoin and Ether"
If that is true, I think he is very optismistic.
ROFL. Read it again, he said the exact opposite. Holding 90% of your assets in anything is stupid/naive/uneducated. Any investor knows you need to spread out your assets into different markets and different asset mixes. If you go all in you're raising your risk exponentially.