Here's the thing: the UK needs trade agreements in order to thrive. The EU may be only minimally democratic, but the fact that the people get any say at all in the terms of that set of trade agreements is considerably better than the say we'd get in any other trade agreement. Especially given that we would be the minor partner an any trade agreement we made with powerful partners: we'd be letting the USA, for example, dictate to our government. If we ever do an agreement with the USA, you can bet that it would come with rules about generic drugs, and allowing them to buy up our schools, hospitals and prisons -- and the people would get no say at all.
Meanwhile the EU, for all its faults, has rules based around human rights, environmental protection, animal welfare and mutual prosperity. That's the type of trade agreement that we want. Nothing on offer outside the EU will be as kind to us. Nothing.
Not only that: being out of the EU has cost us 5% growth per annum. Our exposure to global catastrophes has been worse, and our recoveries slower, than EU countries and comparable economies. Our labour market is a mess, our exporters are inundated with paperwork, and our governments, without the leavening influence of the "undemocratic" EU, have been more corrupt, more cruel and less respectful of human rights.