Does that mean when you buy bitcoins on Robinhood, Coinbase, Coinbase Pro, Gemini, or even the trust GBTC, they are all Web Wallets?
I think Robinhood doesn't even allow us to move the private keys to our wallet, while Coinbase, Coinbase Pro, and Gemini do.
GBTC, I am not sure: if they store the bitcoins "cold" in their trust, then maybe it is not as insecure? Robinhood also said they store a good portion of their bitcoins "cold", and I suppose they only move a small portion to their platform to satisfy the trading or the exchange-for-cash?
So should we consider Robinhood, Coinbase, Coinbase Pro, Gemini, or GBTC Web Wallets and avoid using them for too long but should transfer the private keys into our own wallets?