When we were in the EU the others had to be respectful (if not overly chummy) because of our intellectual contribution, financial muscle, economic clout, etc.
Whilst the EU is a different animal from the Common Market days (and not necessarily for the better) it will have to change because of problems like Italy, Greece etc - and we could have made those changes happen because of our clout etc.
So given we were long-standing members then remaining was the only intelligent position to hold because whilst no-one could accurately forecast how calamitous the outcome of the negotiation to leave would be, a child of 5 with an IQ above 50 and a few months of playground experience would have already had enough life-experience to know that leaving would be a disaster because of spite and revenge prompted by rejection etc.
And so it has come to pass.
But hey! I have just been out for a ride in the sun on my new Italian Bianchi/Campagnolo 22 speed, after going shopping in my German car and I am now sipping a lovely French White Burgundy and planning my next holiday in Finland (EU Member since 1995)...and life will go on.