1. Thats not the question. People did not vote to leave the most damaging way possible to the economy.
2. Correct, the UK will not maintain its position in the global economy. I don't think there is much doubt at this, it is going to enter a serious period of decline and wont be in the top 20 in future.
"One that benefits the UK". You actually believe all the guff you come out with? Once the UK leaves the EU without a deal it will need to go round begging for whatever deals it can get. What a starting point for any negotiation. The EU isn't going to abandon Ireland to make the Tory party happy either, the final deal is no way going to "benefit the UK".