I don't have a local credit card. I've read on here that they can be hard to get without a work permit/source of funds or that your need to provide collateral.
I don't have a local debit card either, still working on that. but when I do I won't keep very much money in that account. I'll transfer cash in from another account as needed. I'll also keep a big wad of cash in my pocket as backup.
but you don't need a credit/debit card to pay for stuff with the Bangkok Bank (BBL) app. a lot of merchants use the QR code system to accept payment.
for example, my electricity bills have a small QR code printed on them. I use the BBL app's Scan function to read this code. it pre-fills the payee and the amount. then I confirm payment by entering my PIN. so I have total control over the funds from the get-go.
you can also use this QR code system at other merchants although it's not as widespread as it could be. eg. my local Seven doesn't seem to support it.
as for their beer prices, will I live in Lumphini, Bangkok and don't have a car so it's easier just to do the short walk to the local inconvenience store. if you buy in bulk you drink in bulk is my experience.