Why is this bitcoin so complicated? No, it's not bitcoin is an entry on the (public ledger) blockchain that says a particular address has an amount of bitcoin and to transfer/move the bitcoin to a different bitcoin address(es), you need the private key Why does it require so many difficult tasks, like Linux, hard wallet, cold wallet, data centers,? It's to secure the private keys, but none of it is required Coinbase has a lot of bitcoin, so does Michael Saylor, so does Satoshi, also there's a bitcoin ATM i n the gas station? They have the private keys that correspond to bitcoin addresses the private key must be some super encrypted password that is very difficult to decrypt, needs quantum computer? it is not encrypted. private key is just a number 1 is a number, can it be a private key? yes, but everyone knows it and if you send bitcoin to the bitcoin address associated with it, there are scripts that will immediately transfer the bitcoin to their address, A week ago, someone sent $5 worth and it was transferred right away why these complicated bitcoin wallets and setups? bitcoin wallets allow you manage the private keys easily, but they are not required, if you're a good developer can use a python script or something to use the private key utilize the network stack, and broadcast a transaction, you don't need a copy of the blockchain which is over 750GB in size If I want to take the 1 Million bitcoin that belongs to Satoshi, I can just guess the number (private key)? Yes, but Satoshi's bitcoin are spread out to over 20k addresses each one has 50 bitcoin on average worth over $5M, so you have over 20,000 chances of guessing the private key for Satoshi's bitcoin and if you guess the wrong one, the one that belongs to the OP's address, you get 10,000 bitcoin or $1.1 Billion instead See how simple bitcoin is? Have fun guessing the private keys https://mempool.space/address/1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm
For relatively small amounts, brokers are also ok. I think coinbase as a vault type of option for long term storage. I used offline paper wallets in the past (a paper print) as at the end of the day your money are a code string of a specific blockchain, but once brokers started going mainstream, safety and compliance procedures, I worry less about storage and take the risk with binance/coinbase. Most times we have go through one of those exchanges to make the purchase anyway.