As you probably know French people tend to moan if they have the slightest reason, and they have similar concerns as British people but they do realise that such a move would damage France. If on the other hand, the UK made a success of leaving the EU, there would certainly be a feeling of maybe we should leave too. However, I know no-one here who actually has said they want to leave the EU.
By the way, I am a very happy -go-lucky positive person in real life. This subject has, however, bewildered me and although personally am hardly affected by it, I can't stand by and just let this nonsense continue unchallenged. As I said, I would be far more aggressive if it was affecting me and it wouldn't be on a football forum.