First of all, keeping your bitcoin on a card or or an online wallet is how you get your bitcoin stolen. You want to use an offline physical hardware wallet to ensure it's safety like a ledger. You can put small amounts on an online wallet when you want to spend, but keep large sums on your physical wallet like it's your own personal bank to keep it safe. Online wallets can be hacked. They also never bothered to talk about the words they mentioned in the beginning. You want to keep your private key to yourself. If anyone has access to it, you can also get your bitcoin stolen. TBC2 is not reliable currency and doubting it has anything to do with etherium. Bitcoin and etherium are the only crytpo I trust. I also would note not to trust bitcoin cash. It has the name bitcoin in it, but it's not bitcoin. Don't trust anything with another name attached to it. The only accurate thing on bitcoin that I saw on amazon was a documentary called cryptopia. Don't expect to know everything after watching it, but it's a great introduction for people who don't know much about the topic.