Unless the argument is fully refuted I am claiming victory. Saying 'whatever' does not cut it. I think we can say now that there are no real benefits to Brexit at all. Even if there were potential benefits (and there were) they have not been seized upon or put into action. Brexit is therefore a complete failure. I am declaring it, so Bri & co can retire. Nice chap, but wrong.
You might want to save yourself some exasperation and a lot of time, by not worrying too much about the strength of your argument. You are dealing with someone totally uninterested in anything other than his own amusement.
If you persist, you will encounter the following:
Dipping into a discussions between others purely to provoke and goad.
When you respond, you will receive requests for information or links that he has no intention of reading, let alone understanding. The technique of debate is then littered with self contradiction and evasion, it will be relentless and he will twist everything to the extent that he hopes you will lose your bearings and forget what the original point was, after which, he will run various accusations from you're confused or confusing him with someone else, or making stuff up/lying. When he inevitably gets caught out, it’s always other people who are bullying him.
In a thread supposedly about the benefits of Brexit, ho hum, you may already have encountered a reluctance to declare how he voted on the subject of the thread, presumably in some attempt to seem above the fray or to play both ends. In other threads you will find the alleged Labour voter employing similar tactics to provoke other voters for the same party.
In short, the very essence of trolling.