People will do the next convenient thing, whatever it is. Re-use containers made of sustainable materials, not buy something on a whim that they do not need, pay more for plastic as an indulgence (obviously it should not be banned, just taxed), etc.

Also, not a psychologist, but I reckon if you dig into what drives people to exhibit consumerism I suspect you’d find things like 1) wealth/status signaling, 2) virtue signaling, 3) just socially having a good time out with friends (shopping is common), 4) stress relief. None of that would be substantially hindered even if disposable plastic is banned outright (which is perhaps a questionable strategy), it would just find other avenues for expression.

Cases where plastic does enable some things that are otherwise infeasible I believe are numerous, but drink containers is not one of them.