Honeslty, I am serious. I am no ICT engineer, but I live with the assumption everything is hackable.
My MacBook air has been hacked, even though I thought my machine was unhackable. Didn't lose anything, but heck it was a scary moment.
I use only use bank cards and cash to make purchases. In rare occasions credit cards (mostly when I am abroad or doing purchases online because I have no other option)
Your instincts are good, but - due respect - your conclusions are not.
Yes, systems are hackable. That's why so many data systems have been breached - Target, Home Depot, TJX (parent company of TJ Maxx, Marshall's, Home Goods, etc.), U.S. Government Office of Personnel Management, Sony, Anthem, and many others.
Here is the crucial point >>> When you use your old "swipe"-type card (debit or credit), your information is captured in the merchant's system. Your information (name, card number and more) is now only as secure as the merchant's data system, which we know from experience may not be secure at all.
Apple Pay is more secure than old swipe-type credit cards and debit cards. When you use Apple Pay, only a single-use token is captured by the merchant's data system. Your information is not transmitted to the merchant (that's why so many merchants are resisting - see below). The merchant gets paid based on the token, so your data remains secure, or at least much more secure than the merchant's data systems have been historically.
Another secure feature of Apple Pay is the immediate feedback. When you make an Apple Pay transaction, the merchant and charge amount are immediately displayed on your phone.
When you mentioned "bank cards", I assume that you referred to debit cards. Debit cards are, in my opinion, very risky. Debit card transactions are immediately deducted from your bank account. Maybe your bank will be cooperative in reversing a fraudulent transaction. Or maybe not. In either case, your bank account balance is affected, likely resulting in bounced check fees, overdraft fees, low balance fees or worse.
Fraudulent transactions using credit cards do not affect your bank account balance. You pay from your bank account only after you see the credit card statement, with plenty of time to challenge unauthorized charges.
You mentioned insecurity of "public networks" in your post #17. This appears to refer to wi-fi networks. Apple Pay uses NFC, which works only when your device is within inches of the payment terminal. This is different from public wi-fi. Further, communication with NFC authenticates with your phone's Secure Enclave. This is hardware, hard-wired in your phone accessible only by your fingerprint. Even if your phone were hacked, through public wi-fi in your example, your Secure Enclave would not be hacked.
Final comments: Some merchants (Walmart, Target and others) do not accept Apple Pay because they prefer a competing system that allows merchants to collect - and use - your identity and data. This compromises security, of course, but the merchants don't care. This is disgusting, in my opinion. One competing system, CurrentC, is promoted by MCX, a consortium including Walmart, 7-Eleven, Target and many others. CurrentC works by directly accessing your bank account and is much more awkward to use than Apple Pay. Fortunately CurrentC appears to be floundering, but many of the MCX-affiliated merchants still do not accept Apple Pay.
Apple Pay's design fundamentally improves your security and privacy, compared to old debit and credit cards and compared to competing systems such as CurrentC. Respectfully, I recommend that you discontinue use of your debit card and use Apple Pay or one of the new chip-enabled credit cards.