You own 0 bitcoin until you hold your own private keys. Get comfortable moving bitcoin around onchain first though. nostr:npub1rxysxnjkhrmqd3ey73dp9n5y5yvyzcs64acc9g0k2epcpwwyya4spvhnp8 has many great tutorials on YouTube.
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Also, watch out for scammers trying to perform phishing or social engineering attacks on you now that they now you have a fat stack on Coinbase.