So there appears to be a scale between anonymity and security. There is Coinbase on the one hand with high security and then physical meetups with high anonymity.
Yes, a neat thing about Bitcoin is people can use it however they want.
For example, I have no interest in using or selling drugs, but that's one of the biggest markets for Bitcoin because people can actually do it in a much safer way than meeting in some dark alley. So even though I don't use Bitcoin for that I don't necessarily want to give Coinbase access to everything I do with my bitcoins, because it's none of their business, even if it's totally legal. I have a coinbase account, but it's just for buying bitcoin conveniently. If I then want to use bitcoins to gamble for example I probably would send those coins from coinbase to some other site, like an exchange, then withdraw those coins to another exchange then maybe one of my other wallets like with blockchain.info. That way Coinbase can't accurately track where I sent the coins I bought from them. Hope that makes sense.