How have "financial people" overturned Brexit ?
There are two ideologies working here, various names have been used, here I'll use (drastically simplifying and exaggerating a bit)
1 liquid capital - this is the world of borderless money that cannot be tied down to any county, the ideology (in its purest form) requires total subservience to economic ideology and is against any manifestation of national governments that try to place restrictions on the flow of money, this leads to immense stratification (between and within countries) and alienation of the elite from the citizenry who are ultimately regarded as a burden ("useless eaters")
2 nation state - the idea that some things are more important than economic balance sheets and economic figures and that money should not be able to flow anywhere and everywhere that those who acquire it desire, it starts from the premise that governments are supposed to represent the citizenry first and foremost and that it is immoral (pour example) for the UK government to welcome rich Russian oligarchs who are, without exception, murderous thugs and thieves
The whole remain campaign seemed based entirely on the ideology of liquid capital which leaves non-elites (and those with no aspirations to be financial elites) emotionally cold which is a contributing factor to its loss. For most people, the nation state is the better bet as its thanks to the nation state that we have things like public education and some publicly funded healthcare etc (which the forces of liquid capital are busy dismantling as fast as they can). If Brexit is overturned I would expect even faster and stronger dismantling of institutions that are intended to serve the public.
It's an economic variation of the globalization vs nationalism dynamic (or 'diversity vs solidarity') that forms the largest ideological divide in the western world today.
It's interesting just how powerless the UK, as a nation state, has been against liquid capital in the post Brexit referendum world....