didn't tell them not to get medical insurance. Just told the OP it's not a requirement for a Non O. I assume they are adults and can make that decision.
Unfortunately it is hard to say what will happen as it all depends on the Immigration Officer you encounter. Some people are lucky but like Brandon said there is a good chance they may send you packing.
not necessarily true with Bangkok Bank as I received pop up messages when I tried to open the app telling me what needed to be done to keep the account active.