See what happens in Brazil: companies like Mercado Livre and Nubank offer the user the possibility to buy cryptocurrencies, but they do not offer wallets or keys, so we know that the real ownership of cryptocurrencies is not the user's but the company's, however many people lack of knowledge or looking for facilities ends up choosing to buy anyway.
If a company like that wants to, they simply add all the assets of the clients. We really need to invest in financial education, especially in emerging countries.