Need help understand how to use Cold Wallet

Hey there,

I recently started buying Bitcoin using Coinbase and someone commented on one of my posts suggesting that I move my coins to cold storage because they aren't technically mine on Coinbase. However, I didn't receive a response after I asked for clarification, so I thought I'd create a post to ask for more information.

My understanding is that cold storage is like a wallet that can store my coins offline. Can I transfer the Bitcoins I bought on Coinbase to a wallet? If so, which wallet is the most recommended? I've looked through some recommendations, but people mostly refute them due to past problems or leaks.

I also have questions about gains and losses. On Coinbase, I can see the current value of my coins, but if I move them to cold storage, how can I see their value? If my holdings are worth $1,000 now, how can I get the exact value of the coins if I need to withdraw them in the future? For example, if my coins are worth $3,000 in 10 years, how can I be sure to get that value?

Where is the best place to buy and sell cryptocurrency? If Coinbase is good, I'll keep using it. But if I need to sell for cash in an emergency, where should I go?

Thank you for your help!