it's true that the number of bitcoin wallet users is still very small, but I strongly believe that number will increase over time.
Because not all people in the whole world know cryptocurrency or using blockchain but for me this is a huge number of blokchain wallet in the next 10 years I'm sure this number will increase because of being popularity of cryptocurrency.
but not all of that 35 million wallet are the numbers of people using the blockchain wallet also.
There are many peoples who have not just 3 wallets but more.
Soon in the near future, everyone will have those wallets.